


It's a Scent Thing

by TheBeingOfEverything



Category: Ao no Exorcist | Blue Exorcist
Genre: Aged-Up Character(s), Blood and Gore, Chair Sex, Claiming, Claiming Bites, Demon Sex, First Time, Gratuitous Smut, M/M, Masturbation, Mating Cycles/In Heat, Office Sex, Orgasm Delay/Denial, Other, Outdoor Sex, Overstimulation, Pheromones, Porn With Plot, Pre-Relationship, Riding, Rough Sex, Rutting, Scent Kink, Self-Lubrication, Tail Sex, Threesome - M/M/M
Language: English
Status: Completed
Published: 2019-09-01
Updated: 2019-09-01
Packaged: 2020-10-04 12:34:26
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 24,283
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20471111
Author URL: https://archiveofourown.org/users/TheBeingOfEverything/pseuds/TheBeingOfEverything
Summary: "When you called and said you needed me in Assiah, I didn't think this was what you had in mind.""Trust me, Amaimon, it very much wasn't, I had no idea he was even capable of these heats."Rin's issues happen to include more than being in a tug of war between the two halves of himself. Now, they include demonic hormones, too. If his body doesn't kill him before the week is up, he might settle for killing Mephisto.At least Amaimon is having fun.(As always, characters are aged up appropriately, and the demon kings are NOT related.)





	It's a Scent Thing

**Author's Note:**

> So… I did it. I gave in and wrote a heat fic and I’d be ashamed of myself if I had any shame left to give after Incandescence :D
> 
> I thought, gee, there’s really a dearth of good heat!fic in this fandom (with maybe 4 I’ve read and actually liked, which are all bookmarked here and on my ffnet if you guys wanna check those out~). So, of course, the first paragraphs were already typed up in my phone notes and this sat in the void of all my wips for a few months.
> 
> Then, because I am weak, I started adding bits and pieces and here we are!
> 
> Hope you enjoy my heat!fic rendition~
> 
> Song(s) of the fic: Painkiller by Dreamers https://www.youtube.com/watch?v=E5NJG1zRKj4  
Howl by Florence and the Machine https://www.youtube.com/watch?v=JZweDwbJ_Ic

Rin woke up in a haze, supremely uncomfortable, and it took his sleep addled brain a moment to catch up to the cause. He blinked down at himself, seeing that he'd sweated through his clothes in the night somehow.

"Ugh, gross, what the hell?" He mumbled, plucking at his shirt where it stuck to his chest and grimacing when his scent hit.

Shower, now. Rin shuffled to the dorm showers, shivering when the blast of cold water woke him up further and he realized he had another problem.

Rin thanked whatever deity was watching that he'd woken up too early for even Yukio as he reached down to take care of said other problem.

He bit at his lips to muffle any sounds, hand pressed to the cool tiles as he stroked along his length. The heat radiating off his body building until he trembled where he stood.

Hot water stung at his skin and sent his pulse racing with his increasing pace.

"Mmn- hah," he gasped, tail lashing in the puddling water on the floor and he realized he'd cut his lip on his fangs.

Rin's eyes shot open, tongue sweeping over his bottom lip before he could stop the automatic reaction and the taste of his own blood sent heat straight to his gut.

His hand gripped the wall as he came with a silent moan, hunching to touch his head to the slick tiles until he recovered.

What the hell was that? Rin stared at his hand, seeing claws had formed at some point. He flicked his tongue against his lip again, though the blood had washed away in the shower already.

Why would his body decide blood was something to get excited about? That was weird, right?

He sure as hell wasn't asking Yukio about something like that.

But at least he'd calmed down, finishing his shower in peace and making sure any trace of his release had gone down the drain before he left to get an early start.

Yukio would be proud of him for not sleeping through his alarm again, at least.

* * *

A hyperawareness seemed to follow Rin throughout the day.

Every time someone passed him in the hall he found himself focused on them to the point he could hear their hearts beating in their chests and the breaths they took.

What was weirder was when he couldn't move out of the way in time and got brushed against.

His whole body tingled, an itching beneath his skin that persisted long after he left the person behind.

"Hey, Rin."

"Ah!" Rin yelped, almost jumping out of his skin when a hand clapped his shoulder.

"Geeze, jumpy much?" Shima said, eyeing him and ruffling the offending hand he'd pulled back to his hair.

Rin wanted to grumble but knew it wasn't Shima's fault he was so off-center that day. "Sorry, man, I spaced out or something."

"You get any sleep last night?" Shima's question as they walked to their next class had Rin freezing, though he was quick to continue before Shima could notice.

Because that innocent statement hit close to the mark and brought the reason for Rin's strange mood right back to his mind.

"Uh, no- no I kinda woke up way too early so I guess it threw me off today," Rin managed to reply.

"Hah! I haven't slept the whole semester, you should pull some all-nighters like I do then get back to me."

"I don't know how you do it," Rin said, going along with the conversation but not really in it.

He spent the rest of how day at turns ignoring his body and trying to figure out what was happening and if he should be worried.

If it got worse, he would talk to Yukio about it, Rin determined.

Not that it made it any easier to concentrate, but he got through classes without attacking anyone who accidentally touched him, so Rin considered the day a success.

* * *

"You don't want to go hang at our dorm, Rin?" Konekomaru said, brows furrowed in confusion.

Rin shook his head, saying, "nah, I think I'm gonna try to get all that reading done and go to bed early."

A snicker burst from Shima's mouth, his hand coming up to wave away the glare Rin sent him. "Who are you, and what did you do to Okumura? Did you and Yukio swap places?"

"Hey! I can study sometimes, dammit," Rin snapped out, scowling when it just made Shima laugh outright.

"I'm glad Rin- although I'm sure Professor Okumura will be even gladder," Konekomaru said, elbowing Shima as he tried to smooth the irritation in Rin.

Which, he didn't even know why he was so flustered in the first place, since usually Shima's comments slid right off him, but not today.

"Whatever, I'm going home, I'll see you guys tomorrow."

He left to Shima and Konekomaru's concerned comments about his mood they thought they were being subtle about.

But Rin's senses seemed to be more heightened than they'd ever been outside of when he'd unsheathed the Koma sword.

So the oddly enticing scent that caught in his nose had Rin taking a detour across campus that he wouldn't have otherwise.

-Only to see the small white-dogged form of Mephisto, pink polka-dotted bow-tie and all, walking through the courtyard.

"There's no way," Rin muttered to himself after a pause to think about if he'd really be following the scent of his demonic headmaster and whether he really wanted to keep following that train of thought.

Mephisto stopped, ears twitching as he glanced back and saw him staring.

A poof of pink smoke later and Rin had to look up at the form that now towered over him.

"Okumura," and then Mephisto leant forward, crowding into his space with his ridiculously tall body, "are you wearing a new cologne, perhaps?"

Rin squeaked when Mephisto literally sniffed his hair, stumbling a few feet back. "No? I just showered this morning with whatever we've got in the dorm bathroom that Yukio buys."

His abrupt departure from Mephisto's side and hurried answer had Mephisto blinking as if coming back to himself. He shook his head and sent a sheepish smile towards Rin.

"My apologies, I could have sworn I picked something up from you, don't let me keep you, then, Rin."

And with that, Mephisto poofed away in one of his pink clouds, leaving Rin very lost, and very unsettled.

Because for a moment there, he'd been overcome by something and almost leaned into Mephisto, too.

Rin shook his head, dispelling the weird urge, and hurried home.

* * *

The next night was even worse than the one before.

"Dammit," Rin hissed, throwing the sheets aside- he'd foregone the blanket after the first time he'd woken up that night but now even the sheet was too much.

Dammit, dammit, dammit! Rin continued the litany of curses in his head the whole way to the bathroom.

He knew without looking that it wasn't even nearing dawn and that he'd twisted himself awake earlier than the night before.

And the damn heat was back, an insistent weight that made every step urgent, the call of the semi-privacy of the showers almost a mantra.

"Rin?"

Rin's heart leapt into his throat at the sleepy sound of his name.

"Kuro!" Rin yelped, hand coming down from the defensive fist he'd raised to his chest. "What are you doing up? And don't sneak up on me!"

Kuro blinked at him, tiny fangs revealed when he yawned. "I've never seen you up this late, Rin, are you okay?"

"Ye- yeah, Kuro, I'm okay," Rin said, glad that the shock had woken him up from the trance he'd been in. "I just got too hot and I needed a shower or I'd stink tomorrow in class."

"Stink? You smell good, Rin," Kuro said as he cocked his head and sniffed, expression crinkling in concentration.

"It almost smells like-" Kuro frowned, cutting himself off in dismissal."-nevermind, there's no way, you're half-human."

"Wha-?" Rin barely got out the questioning word before Kuro already turned to walk back down the hall with a goodnight thrown over his shoulder.

"Okay," Rin drew out, scratching at his head alone in the hall.

The hall that was starting to feel stifling again.

"Dammit, not this again," Rin groaned, jogging the rest of the way to the bathroom and _really_ hoping there weren't any more interruptions.

When he found release that night, the memory of a scent tickled the edge of his awareness.

This time, he bit his lip until he bled on purpose.

* * *

"Pay attention!"

A thwack echoed in the old cram class alongside Rin's exaggerated shriek of pain.

"Ow, Yukio, what the hell?" Rin said as he rubbed the welt where Yukio had thrown the chalk eraser at his skull with pinpoint accuracy.

"This is the fifth time you've spaced out all class, Rin, and I was calling your name this whole time," Yukio growled, patience for Rin's antics at a limit. Especially since he'd just returned one of Rin's graded tests with a dismal score.

"You still not sleeping right, Rin?" Shima asked, getting a raised brow from Yukio at the revealed information.

"Rin?" Yukio said, looking a bit more concerned for him than before when he turned his gaze back to Rin.

He sighed, knowing it was time to come clean to Yukio or risk getting yelled at even more. "Yeah, I haven't been getting sleep this whole week, I keep waking up in the middle of the night and I can't get back to bed."

"Oh no, maybe I can make you some chamomile tea with valerian to help, Rin," Shiemi offered, green eyes wide as she entered the conversation too.

Rin smiled at her, feeling a bit better, even if the thought of drinking tea didn't sound appealing at all for some reason. He had to resist scraping his claws to his neck, a sudden bout of anxiety hitting.

Wait, Rin shot a quick glance at his hand.

Black claws tipped his fingers where usually pale pink human nails would be.

What the actual hell?

The anxiety ratcheted up an extra notch, Rin forcing the claws back to his normal nails.

Maybe…

… Maybe it wasn't because he was sick.

Demonic, everything that was happening to him involved his demonic senses.

Rin knew of only one demon who might know the answers, much as he wasn't sure he wanted to ask.

"Hey, I think I'm gonna go, Yukio, I don't think I'm feeling good," Rin mumbled, already rising from the desk and heading to the door.

"You still need to get the notes later, Rin, but get some sleep, okay?" Yukio said, worry tinging his voice as he let Rin go without complaint.

Mephisto, Rin had to find Mephisto.

His nose flared, searching for a particular scent in the air.

Somehow, despite being nowhere near Mephisto's office, Rin found the scent.

He followed it.

* * *

Rin blinked, the elegant doors to Mephisto's office staring back at him. He didn't remember the trip he'd taken there.

It didn't matter. He pushed the door open, knowing Mephisto was inside.

"Excuse me- Mr. Okumura?"

Confused green eyes narrowed at his entrance, Mephisto being in the middle of a phone call that he'd interrupted.

"Mephisto," Rin said, voice low as he struggled to get the words out, his throat thick until he coughed. "Something's wrong with me, I don't know what's going on."

That got a frown twitching at the corners of Mephisto's lips as he spoke into the phone, "I apologize, I'll have to call you back, a situation has come up that needs my attention."

He hung up, phone poofing away in one of his pink clouds. "Now, what, exactly is wrong that you think I can help with that your brother or a nurse can't-"

His question cut off, nostrils flaring as he scented Rin out. Green eyes widened, then narrowed again, this time like he was solving a puzzle.

"Rin," he said, slowly, while his hands met in front of his nose to hide the rest of his face, "describe the symptoms for me, please."

If Rin had been thinking at his usual levels he would have seen the odd way Mephisto now looked at him. But all he could focus on was the way the scent he'd been following filled the room, cloying in its intensity.

"Just- hot, I've been feeling hot," he started, tripping over the words and searching Mephisto's expression for answers. "I can't sleep and- I don't know, my claws came out in class today and I can hear _everything_ in the halls now."

He sucked in a sharp inhale through his nose, the sweet scent hitting him like a lead pipe across the face.

His fangs were extended in his mouth. Rin swept his tongue over the points of them, an absent action as he fell into the rhythm of relating his problem.

The sharp pain that came a moment later brought him to the present in the next instant, eyelids fluttering rapidly as he tasted the blood coating his lips.

"You smell-" Rin stopped himself from completing the really creepy sentence. He'd been about to say "good" like that wasn't the weirdest thing ever to tell someone you weren't dating to their face.

"Well, normally I'd be offended by that statement," Mephisto said with an arched brow, folding his hands to rest flat on the desk as a knowing smile formed. "But I have a feeling I know how you were going to finish it."

A blush crept over Rin's cheeks, body heating further at the slip-up and consequent teasing.

"So? What's wrong with me?" He said and crossed his arms, muscles tensed so that it became more of a hug he'd wrapped around himself as he glared at Mephisto.

"It's a little quirk of the effects of our powers on a vessel, entirely based on levels, right now your instincts are telling you mine is greater than yours, though, given who your power comes from, that is bound to change."

"Stronger than me?" Rin stuttered over the question, because what?

"Yes, I suppose reintroductions are in order, though I didn't think I would be giving them this early on."

Rin stared as Mephisto bowed his head, green eyes glinting under his brows as he smiled.

"My name is Samael, second in Gehenna under Satan and demon king of space and time, a pleasure, Rin Okumura."

_What_?

Rin couldn't comprehend what Mephisto had said. The words made sense individually but together the meaning fell apart.

"You- what?" He got out, still unable to get the utter confusion he felt into words.

"On the side of humanity, of course," Mephisto said, hand waving the revelation aside like it hadn't shook Rin to the core. "I love the chaos of this world too much to let it be destroyed by Father."

"Now, the matter of your heat," he continued.

"Wait! Seriously, you bastard?" Rin shouted, interrupting Mephisto as he clenched his hands into fists at his waist, breaths huffing out of him at the anger coursing through his body.

"Yes? Seriously what, Rin?" Came the sly response.

"You're some super strong demon and you're just telling me now? What the hell?" Rin completed his tirade and grit his teeth.

The smile on Mephisto's face widened into a full on grin that bared fangs. "Oh, did I forget to mention that? My mistake- did you want help with your problem or not, I am a very busy demon and you came right in the middle of a call, remember?"

"Argh! Forget your call!"

Rin stomped towards the desk, fury now pulsing in his veins.

He reached the edge, a snarl twisting his lips but, as he began to speak, he made the mistake of inhaling a deep breath.

A choked gasp was the only thing Rin managed, stumbling back from the desk, sightless as Mephisto's scent hit him in the nose up close.

His mind flashed to that moment in the courtyard when Mephisto had leaned into his space, body enveloping his before he'd stepped back.

Whimpering, sounding from far away, reached his ears as Rin became aware of it. Not that it meant anything to his scattered brain.

Not when the heat was back with unholy vengeance and _infinitely_ more insistent than he'd ever felt until that point.

The cold sweat had returned too, but there was something else that had appeared with it, a sensation he couldn't place beneath his tailbone.

It was…

A slickness, not related to sweat at all and not something he thought a human- particularly a _male_ human- could be capable of producing, now made an uncomfortable wet stain on his pants that Rin burned in humiliation to feel.

More than that, more than the shame...

...Hot, he was so hot. He needed to release it somehow- needed to not be so constricted!

Fire flared into existence around Rin with a cry as he dropped to his knees, wide eyes staring into the blue flames while he panted in the inferno.

Some of the pressure relieved with the energy expenditure, enough that Rin could think a little clearer.

But not enough to take it away completely.

"Mephisto," Rin gasped, "why won't it go away?"

His flames flickered and died when even that effort stopped having a noticeable effect.

Rin fought the frustrated whine that tried to come out. He clenched his fists to the carpet, body broken in a sweat and knowing his expression was verging on desperate where he cast it up at Mephisto for a solution.

"Make it stop, please make it stop, Mephisto," Rin said, voice definitely a whine then, while the heat buffeted at his insides, skin flushed and tears pricking the corners of his eyes.

It was only then that he realized he'd burned through his uniform, the threads of the carpet itching maddeningly where it touched his skin.

He wanted to burn the carpet too. He wanted to burn _everything_.

Mephisto watched him with a look he couldn't place at first, somehow unmoved by his actions.

Then Rin realized what the look in Mephisto's eyes was.

Hunger.

"There's only one way to make it stop, Rin," Mephisto finally spoke, voice deepened by the rumble that had started coming from his chest.

"How, dammit?" Rin growled the question, willing away his impulse to touch himself because the idea of being like this in front of another person was mortifying enough already.

His hands twitched at the thought where they covered his lower half from view, almost giving in and moving the rest of the way.

"I think you know the answer- or you would if you stopped ignoring your own body," Mephisto said as if that were any kind of real answer.

"That's not-" Rin tried to get out.

A gloved hand waving away his words again had Rin glaring harder at Mephisto. The shaking in his limbs grew even more difficult to ignore, but he stubbornly persisted.

"The answer to your problem is simply to give in, Rin, and go back to your human concerns after this week is over."

Give in, seriously? Rin almost shrieked out, except a new wave of sensation had him hunching forward, legs coming together to squeeze himself between them as the slick at his entrance seeped onto his ankles.

"What- _ha_-ah what kinda option is that?" Rin panted, squinting up through his bangs that had plastered themselves to his sweat-drenched skin at the unwavering gaze pinned to him.

He wanted more than a gaze on him, wanted hands other than his own pinning his body.

He'd zoned out, coming to with a low moan when a new pressure sent further heat coiling inside. Rin yanked his hand back from where he'd started stroking himself in his distraction, feeling the ache of loss right after.

The tendons in his body creaked at the strain of holding still. Rin wanted to climb the desk to get to Mephisto.

"While you still have your mind, Rin," Mephisto said, voice nearly hypnotic with how attuned Rin was to his every move, "do you accept my help and any judgement of mine in the help you will need? I wouldn't want to be ungentlemanly, you see."

Rin choked on another whine, eyes clenched as the word "help" from Mephisto brought images of all the ways he wanted to be helped to the forefront of his mind.

"Yes!" Rin gasped before he could think about it, needing to get rid of the horrible ache and desire to find anyone to satisfy his instincts before they overwhelmed him completely.

If Mephisto could make it stop, could prevent him from going to someone he didn't even know- worse, one of his friends, then Rin would take his help.

A pleased hum from Mephisto had Rin wanting to snap at him for dragging things out instead of _moving_.

"Mephisto," Rin grit out between his elongated fangs.

Tapping at the window of the office wrenched Rin's head to the side, heart jolting at the thought of someone seeing him in his state.

Billowing smoke and a poof later had Rin shouting in surprise, face flushing with embarrassment the moment it cleared to reveal a new person.

Who?

The person scanned his trembling form, somehow expressionless despite the scene he'd entered into, and ignoring him in favor of Mephisto.

"How many times have I told you to use the door when you come here?" Mephisto sighed, cheek resting on his knuckles.

How could he be so calm? Rin wanted to set the both of them on _fire_ and he didn't even know the newcomer.

"When you called and said you needed me in Assiah, I didn't think this was what you had in mind." Came the lightly probing words instead of acknowledging Mephisto's complaint.

"Trust me, Amaimon, it very much wasn't, I had no idea he was even capable of these heats."

The new person- another demon? Had to be with the black daggers he had for claws- knelt down to peer from wide gold eyes at Rin.

Then Rin yelped as one of those clawed hands slid down his spine to trace at his slicked entrance.

He used the last of his reasoning to hiss and slash at the questing fingers, fighting the moan that wanted to escape at the loss of that contact when the demon backed off.

"What's the matter, why won't you let me play with you?"

"Play?" Rin panted out, flush rising at the pout on the demon's face, "I don't even know you!"

"Why does that matter, I'm strong and you need it, why resist?" The demon glanced at Mephisto as if looking for a satisfactory answer.

"Go on, then, introduce yourself, Amaimon, it's only polite here in Assiah," Mephisto said, a sly smile exposing fangs as he watched Rin with acid green eyes.

Before Rin could object that one introduction was not enough to go on for something like what they kept implying, the demon pushed him down to the floor.

"Ah! Hey!"

"I'm sorry, my name is Amaimon, demon king of Earth and seventh in Gehenna under Satan, and you are Rin Okumura, spawn of Satan, inheritor of the blue flames of Father."

The weight pressing him into the carpet sent his instincts screaming for more and Rin almost sobbed at the friction of Amaimon's knee between his legs.

He thrust his hips to get more of the delicious pressure, throwing his head back and scrabbling at the floor.

"I think he's ready, now, Amaimon, welcome to Assiah." Rin barely heard Mephisto through the pounding of his pulse in his ears.

A sob broke past his lips anyway when Amaimon moved, his absence drawing Rin's eyes open to search him out and bring him back.

His throat went dry when he saw Amaimon removing his clothes, the maroon coat dropping with a soft thud followed by a slither of fabric before his tie joined it.

More and more skin revealed itself to Rin until Amaimon stood naked before him, a cocked head and appraising eyes scanning his trembling form.

Movement caught his eyes as a slim, green lizard-like tail uncoiled from Amaimon's waist to wave with slow intent at his feet.

And Rin couldn't take it anymore. "_Please_, I need- I need-"

Rin cried out when Amaimon kneeled back over him, palming him in a firm slide over his length that had more pre-come joining the mess the slick made on his body.

He jolted as a blunt head rubbed at his entrance and a small part of his mind returned with the alarm.

"Hang on," Rin gasped out, hand moving down to try blocking himself from the length teasing at his rim, "don't you need to do something first?"

By the blank look in Amaimon's eyes he couldn't seem to understand what Rin meant. Not that Rin knew anything about the subject himself but he could have sworn there was more work involved than _this_.

"You heard him, Amaimon, it's his first time, be a gentleman and prepare him," Mephisto said, chin propped in his hand as he grinned down at them.

"Ah, okay, I didn't realize, I'll be more careful."

Then fingers circled at his entrance, pressing in before Rin could understand what was happening and a burning stretch sent him arching back to the floor.

"_Hah-ahn_," Rin let out another wordless keen, spreading his legs and canting his hips to get the intrusions deeper inside

More, he needed more.

What was that demon's name?

"Amai- _Amaimon_," Rin said, unable to think enough to form complete sentences and desperately hoping he'd be understood.

"You're lucky, Amaimon, he usually doesn't learn names this quickly."

Mephisto's teasing voice took a fraction of Rin's attention away from the sudden loss of Amaimon's fingers from inside.

Before he could make a sound of complaint, his breath escaped in a whoosh as Amaimon sank into him without warning.

Rin lay there beneath Amaimon, vision whited out and eyes rolled back in his skull, stunned.

Good. It was so _good_.

Every one of Rin's nerve-endings and instincts were on fire, finally getting what they'd been pushing for.

The first sharp thrust shattered the daze he'd fallen into and jolted Rin into action.

He wound his legs around Amaimon's hips, trying to get him as deep as possible while a stream of nonsense-sounds slipped from his lips.

Rin needed to get closer. His tail, which had been twisting at each slam of Amaimon into him, shot up to twine with Amaimon's where they brushed.

His back slid over the carpet when the drags he drew with his tail along Amaimon's spurred him into higher gear.

A hiss through bared fangs made Rin tilt his head back to expose his throat without hesitation, lost to his instincts telling him to submit to the stronger demon claiming him.

Those fangs locked on his presented jugular a moment later, Amaimon loosing a growl that vibrated from the needle-tip points straight to Rin's already edged nerves.

The tension snapped, Amaimon's punishing thrusts hitting something inside Rin right as a red flash of bright pain struck from where Amaimon now lapped at the bite on his shoulder.

"_Ahh_!" Rin screamed as he came, claws sinking into Amaimon's shoulders and gripping tight while he rode out the roiling pleasure rocking his body.

Amaimon snarled, pace increasing and shooting sparks through Rin as the guttural sound right next to his ear short-circuited his remaining awareness.

Warmth pooled into Rin followed by the sensation of being utterly filled as Amaimon released with a last erratic snap of his hips and stilled.

He lost time, drifting in the afterglow under Amaimon's shuddering frame, his mind finally cleared from the cloud of his heat.

Something- a soft thud slowing from its rapid pulse- had his face tilting on its own to nuzzle into the source. Rin inhaled, the source he nosed at shifting at the touch.

The shifting had Rin opening his mouth to let his tongue lave at the pulse in Amaimon's neck, chasing the beat of it and humming with contented pleasure when it skipped at his ministrations.

Another sound reached him as his senses returned one by one. A purr he eventually registered as coming from his own chest the only thing besides their mingled breaths in the room.

“Don’t get too comfortable on my floor, Amaimon. I don’t need you falling asleep there, I have meetings today.”

Rin froze where he’d been mouthing at the pulse-point, eyes shooting open fully as he came back to reality.

His lips unlatched in a yelp, Rin going from pulling Amaimon closer to shoving back- even if his frantic actions didn’t do much to shift Amaimon at all.

“Get off!” Rin shoved again until Amaimon relented and sat up with a confused tilt to his head.

But the motion just made Rin aware of the state he was in now, a sticky mess of fluids across his chest and stomach, claws stained with blood from where he’d gouged Amaimon-

-And Amaimon still inside him, though that changed as he disengaged in an abrupt move, release trailing out of Rin to the carpet and sending a hot flush over his face at the sight.

“What’s wrong with him?” Amaimon said, standing and talking like Rin hadn’t been about to ask the same question.

“What’s wrong with me? What’s wrong with you?” Rin shouted at Mephisto as he curled his knees under him, flush extending down his chest when it only served to make a wet noise from more of the mix of release and slick now staining his skin.

“Me?” Mephisto pointed a gloved finger to his guileless face, not that Rin trusted it in the slightest- especially after what had just happened. “I believe it was you who told me to help you as I see fit, Rin.”

“I said _you_ could- could help me, dammit!” Rin snapped, unable to say, exactly, how Mephisto would help.

Unholy glee lit up Mephisto’s gaze, another fanged smirk spelling disaster for Rin.

“Oh? Well if it’s me you want, I would be happy to oblige, I didn’t know you felt so strongly, Rin.”

“Argh!” Rin gave a strangled shriek, tail lashing behind him in his ire and fuming but the thought of getting up was mortifying.

Wait. He’d been able to somehow control his flames enough to burn his clothes off but not the carpet earlier. He just needed the motivation and the remembered feeling of how he’d done it then. He had plenty of motivation.

Rin stopped seething to flare his flames around him, clearing off the mess on his skin and standing. The flames dissipated, though he had to let the rest out in a hissed breath that steamed in the air before he could speak.

“Fine, whatever, thanks for your help, now gimme some clothes so I can get out of here and forget this ever happened.”

Two pairs of slit-pupiled eyes blinked at his demand before a disbelieving snicker escaped Mephisto’s mouth and Amaimon began to stare at him like he was stupid.

“Oh, Rin, while I can’t say for sure what the exact length or intensity will be in your particular case, your heat is _far_ from over,” Mephisto said, leaning back in his chair and smiling like he hadn’t just delivered horrifying news.

“What?” Rin came forward to slam his palms on the desk, feeling wild-eyed as the thought of that mind-melting pressure and heat coming back absorbed his thoughts. “I feel fine now, there’s no way this is coming back, right?”

Amaimon scoffed and leaned against the edge of the desk next to him. “He doesn’t know anything at all, does he.”

A squeak left Rin’s mouth when he saw Amaimon lick the tip of his finger to clean himself, uncaring of the evidence of their activities on his body and bored expression back on his face.

“No, although in this case I never suspected he might need to,” Mephisto admitted.

“Now,” Mephisto said before Rin could get back to yelling at him, “I will need to write up an excuse of absence for you and you’ll need to tell your brother, I’m sure he’s quite worried about you.”

Oh god.

Horror at having to tell Yukio even the slightest detail about what, exactly, he was going through and what the solution was, had him contemplating throwing himself from the window and ending it all right there.

“Unless you would like me to make up some excuse for you, Rin,” came the sly addition from Mephisto that Rin latched onto.

“Yes! Yukio can never know!” He shuddered, imagining how the conversation would go down.

Mephisto clapping once startled him from his panic, the bright expression facing him having no place after the insanity of what Rin had just experienced. “Wonderful! Now, I have a very busy day to get through before I’ll be able to attend to you, Rin, so you’ll just have to wait for me at Faust Manor until this is all through, hmm?”

“Wha-” Rin wanted to get his claws around Mephisto’s throat for the inanity and self-importance of that statement.

“Amaimon will take care of you for the time being, please don’t destroy my house while you’re there and Belial will know to keep away, ta-ta~”

He didn’t get a chance to object. A snap of Mephisto’s fingers and Rin blinked to find himself in the ostentatious front-hall of what must be Faust, or Mephisto’s, Manor.

And Amaimon slouched beside him, still naked, and holding a hand up to pull a sucker into existence that he absently tongued while his tail swept at his feet.

“Er,” Rin hesitated in saying, edging a few steps from Amaimon as he tried to figure out what he was supposed to do. Also, “aren’t you gonna clean up or something?”

Gold eyes met his in a long stare, sucker rolling between Amaimon’s teeth with small clicks that needled into Rin for reasons he couldn’t say.

“There’s no point, we’re just going to get dirty again,” Amaimon finally responded and, by the scrunched brows, had no idea why Rin was suddenly hiding his face in his hands.

“Fine, I’m just not gonna think about it- it’s what I do best,” Rin said into his palms, voice muffled and ears red at the tips with the blush he thought might be permanent now.

Sleep, Rin needed sleep. It would be the only way he could survive this nightmare and, after a week of not getting enough, he wouldn’t force himself to stay awake.

“I need to find a bed around here,” he said to himself, hands dropping from his face to look around for a hint as to where to go.

“Okay.”

Rin looked over at Amaimon, saw the raised hand, and opened his mouth to object only for the snap to come and another room present itself to him.

“Hey! Stop that!” Rin snapped out at Amaimon as he crossed his arms in indignation.

Once again, his anger got a tilt of Amaimon’s head and not much else.

Just more clicking of that sucker to sharp fangs.

“It’s efficient and saves time, why wouldn’t I bring us here?” Amaimon questioned, sounding genuinely confused about why Rin had gotten mad.

Demon thing, it had to be a demon thing, Rin thought. Amaimon didn’t seem like Mephisto, teasing and knowing full well exactly what he was doing. Instead, he just seemed clueless to human social norms.

“When did I become a teacher?” Rin muttered to himself before sighing and propping a hand to his hip to consider Amaimon. “You could have just asked first, or told me, maybe I didn’t want the efficient way, maybe I wanted to walk, did you think about that?”

Another long stare met his words and Rin wondered if he’d been wrong about Amaimon.

“Okay, I understand.”

“Oh- okay, cool,” Rin was quick to say, not wanting to ruin the small progress they’d made. “I’m just going to bed then, I guess do whatever you want?”

But when he moved towards the massive bed he could see in the room, the one covered in all sorts of weird otaku shit Rin didn’t want to look too hard at, he heard steps trailing behind him, turning to see Amaimon at his back.

“What are you doing?” Rin hesitated to ask, not sure he wanted to know.

“Sleeping.”

Sleeping. By which he meant sleeping in the same bed as Rin because clearly there weren’t a million other beds in the giant house to choose from. No, he had to stay in the one _Rin_ would be in. Rin watched the slow blink of Amaimon’s eyes and knew he was being serious.

He heel-point turned and flopped onto the soft mattress, burying his head in the voluminous pillows and holding back the flinch when the other side of the bed dipped as Amaimon got into it too.

Then it was silent. Just a soft click click click of the damn sucker in Amaimon’s mouth.

The clicks followed him down into sleep when it came to him, not quite lulling, but not as annoying as he’d expected, either.

Dreams came to Rin.

A thick, syrupy liquid coated the black void he found himself in, filling the space and warming his limbs when it began to rise. Rin wanted to thrash but it may as well have been made of tar for all that he moved, struggling beneath the heavy weight as the cherry sweet scent of the syrup lapped at his skin until it was the only thing Rin could smell.

Heat constricted Rin, growing with every inch the syrup covered as the fear of suffocating, held beneath the surface, started sending panic signals to his unconscious mind.

Finally, that sweet scent reached his gaping mouth above the endless pool of red and Rin gagged on the flavor pouring inside, his struggles becoming worse and whimpers choked with the burning in his body.

Rin came awake in an instant, eyes opening to a kaleidoscope of colors before he could orientate himself in the room. The colors settled to become the pink drapes of the canopy bed and hoard of anime plushies.

Then the burning in his body registered- not just a product of his vivid dreams, but what had caused them in the first place.

The honeyed sweetness hadn’t been a product of the dream, either. Amaimon’s scent called as strongly as Mephisto’s had and pressed at his senses in a heady throb while he panted like he’d been in a fight.

He whimpered, sleep-dazed and curling into a ball on the bed as if he could push the heat back down just by that.

It grew worse.

A shift in weight on the mattress besides him had Rin cracking an eye open to search out the source of that scent, nearly sobbing when he saw Amaimon staring down at him, a new sucker in his mouth that he ignored in favor of Rin.

Amaimon shoved him onto his front, his other hand adjusting Rin from the tight ball he’d been unable to move from on his own.

Slick already slid down his thighs from his entrance and Rin, knowing what was to come, couldn’t help spreading his legs while his tail arched in presentation to Amaimon.

Fingers pushing into him a moment later drew a long keen from Rin’s throat, his eyes clenching shut as he dug at the already tangled blankets.

After a perfunctory stretching that Rin could barely comprehend past the need for more, Amaimon withdrew and replaced his fingers with the head of his length.

“_Ahn- Amaimon_!” Rin gasped, drooling into the covers as Amaimon slid inside in one smooth motion.

His tail moved and coiled around the first thing it hit against, tightening into a noose on Amaimon’s arm and forcing another cry from his mouth when the short furs brushed the wrong way.

Electricity sparked maddeningly along his tail and his spine, making his hardened length leak onto the sheets while Rin trembled.

The captured arm tensed, but not for long, hand gripping the base of his tail while Rin stopped breathing at the intense pleasure-pain that shot right up his spine from the sensitive nerves now mercilessly tugged.

Amaimon growled and pulled out almost fully until Rin whined at the emptiness, trying to shove back on Amaimon to no avail as Amaimon held him still.

He moaned as Amaimon slammed into him, forced down onto the mattress with each thrust and sight glazing over. The hand at his hip, bruising in its force, jerked him into a better position, the adjustment whiting Rin’s vision out when it hit that point inside him again and brushed it with each pass.

Rin remained helpless, at the complete lack of mercy from his body and Amaimon, swept away on the tide of the oppressive heat winding tighter and tighter in his gut until-

-Amaimon bent forward, chest a solid weight at his back and the angle forcing him the deepest he’d gone into Rin.

A shout tore from Rin at the shift and then again when Amaimon clamped his fangs down onto the meat of his neck where it met his shoulder.

Once more, warmth from Amaimon filled him while he worried at the ragged gouges he’d made in Rin, muffled snarls sending Rin over the edge soon after.

Like a spring wound too much, the violent claiming broke the crest of Rin’s release and he came, his moan breathless and silent, against the sheets.

It was Amaimon’s turn to trace his tongue to Rin, pinprick shocks jolting Rin’s frayed nerves every time he licked at one of the holes he’d bitten, though they tried to heal.

Heaving breaths, made more difficult by the weight of another body, pressed them together while they recovered. Rin could feel an ache setting in his quivering limbs while he tried to remember how to move.

Moving ended up decided for him when Amaimon grunted, drawing his fangs from Rin and dropping to the side, taking Rin with him so they lay together.

The surprised gasp became a squeak when his tail ended up yanked where it still coiled around Amaimon’s arm.

Over-sensitized nerves in the base of his tail jarred him from the haze he’d entered before.

“You managed four hours of sleep last time,” Amaimon said, the warm breath ghosting over the point of Rin’s ear and making him startle, heart thudding, at the intimacy of it.

Was Amaimon being helpful?

“Good to know,” Rin said in an attempt at casual, though his voice came out thin and reedy as he tried to avoid thinking about the sweat cooling on his body or the scent of blood staining his neck.

A soft snort sent the wisps of hair not stuck to his skin to tickle him as Amaimon added, “it means you’ll probably last another four hours this time before you wake up again.”

Four hours. Rin stared into the face of one of the creepy pillows, bug-eyes cheerful and grinning back at him like he hadn’t just gone a round with a demon he’d met four hours ago and would go again in yet another four.

That decided it, Rin would just have to kill Mephisto later when he had his body and mind back to normal.

He nodded to himself, happy with his logical conclusion and not at all thinking about the fact that Amaimon was still inside him and didn’t appear to be moving anytime soon.

And Amaimon hadn't cleaned them yet either! Rin didn't have the energy or control to figure out if his flames would work without burning the blankets too.

This time when Rin slept, he didn’t dream, but a gurgle in his stomach as he went under reminded him that he hadn’t eaten all day either. He resolved to find something when he woke next.

* * *

“Mmn- ah,” Rin sighed, wiggling back onto the shallow thrusts that drew him from his sleep.

Contentment had pleasant shivers bringing goosebumps to raise on his skin despite feeling like he was trapped in a sauna.

A clawed hand came to rest at his jaw, tilting his head to expose the line of his jugular to sharp fangs that scraped over the rapid pulse Rin just realized was there.

“He’s quite insatiable.”

The hand at his jaw tightened and Rin whimpered at a deeper thrust, trying to climb the last few steps into waking when he recognized the voice.

After a particularly rough thrust, the voice at his ear grunted and spoke, “every four hours, it’s worse than one of ours.”

There was a finger at his lips now. Rin dropped his mouth open on automatic instinct while his brows scrunched, just at the final ledge of awareness, and found it filled with the intrusion.

He sank his teeth down, breaking skin and hearing a sharp curse just as the taste of blood welled up. Rin didn’t release the caught finger, swirling his tongue to chase the flavor and sucking to encourage more to flow.

“That’s- hah- what you get for teasing, Samael,” the voice- Amaimon?- said again, now breathless as the thrusts began to lose their rhythm inside Rin.

Rin moaned around the finger, biting harder when he noticed the cuts closed up and hearing another resigned curse as he re-opened them to lap at the new blood. A light touch settled at the hyper-sensitive skin of his face, the rest of the fingers of the hand cupping there when he wouldn’t let go.

Not that it made a difference to Rin, too focused on the sensations welling up with the fire kindling in his core and washing his mind away in a red tide.

White-hot pain shot through his shoulder as the body behind his groaned in release and clamped fangs into him, wrapping him in arms like iron.

Rin woke at the sudden pain, eyes opened and his teeth extending fully on the finger in his mouth with a crunch of bone.

“Mmf!” Rin gasped the muffled shout around the blood filling his mouth, swallowing before it could escape and dropping his jaw to jerk his head back from the source. A crack echoed as the back of his head met the skull behind him, another shout coming from Amaimon, who Rin just now realized had been the one he’d been woken by.

“Ah!” He yelped, trying to turn his head to see Amaimon and only getting tangled in the sheets he’d kicked at during his sleep.

After a few moments of complete chaos, Rin gave up and lay back on the bed, panting and wild-eyed as he tried to understand what, exactly, was going on.

He found himself subjected to two stunned gazes as Mephisto and Amaimon watched him from the foot of the bed where they’d fled to in their attempts to extricate themselves before he damaged them even more.

Mephisto held his now healed finger in his other hand, shoulders slumped in disbelief, while Amaimon crouched low like he would vanish at the next signs of violence.

“What the _hell_?” Rin blurted out, still panting as he jolted up and fisted his hands to the sheets so he wouldn’t try to wrap them around the two necks he so greatly wanted to wring.

Silence answered him and Rin, flames roused with his ire, let out a flash of fire from his mouth to encourage them to talk.

Instead, he got laughter.

Hands gripped around his chest, Mephisto keeled over so his forehead touched the bed, body shaking at the mirth he let loose. Amaimon just sent a wide, toothy grin at Rin’s infuriated expression and budding growl.

“It seems- ahah!- it _seems_, Amaimon, that we’ve both played with fire and got scorched,” Mephisto said once he’d lifted his head back up.

That got him a frown from Amaimon. “You’re the reason he panicked, Samael, it’s your fault this time.”

“It’s both of your faults, dammit!” Rin snapped, jabbing a claw towards them and baring his fangs to get his point across.

“You!” Rin pointed at Amaimon, getting a falsely innocent blink. “Why would you do that while I was sleeping? You couldn’t even wait until I was awake?”

A snort met his words but, when Rin glared at the offender, Mephisto had that guileless look back on his face.

“And you! Why was your finger in my mouth? I almost bit it off!”

But the effect he’d intended with his questions never hit. Amaimon rolled to lay flat on his stomach, staring at Rin with curiosity as if waiting for him to finish his tirade while Mephisto leant back on his hands with an amused smile, almost exasperated.

Growling, not from Rin’s chest, but his belly, broke his concentration, though it just gave him a new demand.

“And I’m hungry, Mephisto, where’s your kitchen- and some clothes!” Rin hissed the last bit out, really tired of the lack of the latter.

“He sure is demanding, Samael,” Amaimon said, resting his head in his crossed arms, “he really is Father’s spawn, huh.”

“Yes, you can see the resemblance now, from our little dark prince,” Mephisto replied, not caring in the slightest about the glare Rin sent him for that statement and moving to get off the bed. “Well, we may as well eat, since we’ll be a bit tied up with things later.”

Before Rin could remind Mephisto about the second half of his demand, a snap came and Rin jumped in surprise. He crawled out of bed, careful not to step on the robe that had appeared on him and risk a clothing malfunction, and was happy to see he’d been cleaned in the same instance.

A contented hum left his throat as he turned to check that everything was in place. Although, Rin scowled at Mephisto’s smug expression. “You couldn’t give me any underwear?”

“There’s hardly any reason to wear those, Rin,” Mephisto said with a sly quirk to his lips at the blush that colored Rin’s cheeks at the insinuation, “now, follow me, I do want you to be able to find this place by yourself, so we’ll walk there this time.”

With no other choice, Rin followed them into the hall, not without a last sharp look at Amaimon.

Though, the thought of food and having finally gotten sleep- even woken from it the way he’d been- meant his anger lacked heat.

His tail flicked behind him, making Rin aware that the robe he had on was more for someone taller than him and he almost asked Mephisto about why he couldn’t have brought Rin his actual clothes instead of what was clearly one of Mephisto’s robes.

But, Rin rubbed a thumb over the long sleeve of the striped robe, it was probably true that there wasn’t a point to wearing real clothes when…

Well, when the next surge of heat came, he definitely preferred ruining something of Mephisto’s than his own.

Rin had one more very serious question for Mephisto.

"Hey, what's up with all the otaku stuff on your bed, anyway?"

He looked up from under his bangs at the bright smile his question garnered, wondering if the answer was worth knowing.

"I'm glad you asked!"

Rin wasn't glad he'd asked, but at least Mephisto filled what could otherwise have been an awkward walk through the massive manor into something passably like a normal conversation.

By the blank look back on Amaimon's face, he understood Mephisto's answer about as well as Rin did. It probably shouldn't have made Rin feel something like solidarity with Amaimon, but it did, and he was too hungry to think any harder about it.

The entrance to the kitchen came into view.

"Oh, thank god," Rin said, rushing ahead to familiar territory and already searching for the pan drawer to make breakfast.

"Getting comfortable already, hmm?" Mephisto called from behind him, but raised his hands in mock surrender at Rin's glare. "No, please, I think this is under your jurisdiction for the time being, we'll all be much happier for it."

Thoughts of Mephisto's nightmare creation he called oatmeal made Rin shudder. "Yeah, now where's your spice drawer?"

He was going to show Mephisto how oatmeal was supposed to be done.

One look at the fridge in his hunt for the milk, eggs, and vanilla extract had Rin rubbing a hand to his forehead.

"Why is that fish purple and glowing?" Rin asked, a whimper at what he'd just seen growing sentience in Mephisto's fridge.

"Wait, don't answer that, it's not going into my food until I figure out if it'll kill me or not," Rin cut Mephisto off before he could speak.

Then he got to work, mind utterly focused on his craft and finally dropping the tension his day had given him with cooking.

"Just to be sure," Mephisto said when Rin dropped the bowls in front of he and Amaimon, "you do know it's technically dinner now, yes?"

"Who cares," Amaimon said, already pulling the steaming oatmeal to him and eating without any regards to temperature.

"I haven't eaten breakfast yet, so it's breakfast," Rin said in a huff, sitting down across from them and waiting to see their reactions.

The exaggerated gasps and moans of pleasure from Mephisto when he took a bite definitely weren't necessary, Rin scowled, fighting another blush.

But Amaimon's eyes literally glowing from the gold depths and the purr he let out as he guzzled the bowl without bothering to use the spoon had Rin grinning in satisfaction.

"And that's how you make oatmeal, Mephisto," he said, smug, and began to eat his portion.

Before he could revel in his victory, a clack sounded from Amaimon dropping the now empty bowl back in front of him with a command, "more."

The contentment was gone. "How about you ask nicely and I'll even _think_ about cooking anything for you again?"

Wide eyes, cautious at the threat, looked up at him where Amaimon had his chin propped on the counter, an almost comical frown on his face.

"More, please!"

Rin had the vague, horrified realization that he was turning into Yukio, covering it in action by complying with Amaimon.

Somehow, the meal passed peacefully, even though Mephisto hadn’t let him do the dishes afterwards, saying something about a guy named Belial again that Rin wouldn’t be meeting during his week to prevent any tragedies.

“You’d tear him apart, I’m afraid,” Mephisto said when he’d asked, shaking his head as he lead them to the entertainment room. “Your power is just too great for him, he would attempt to answer your call and be destroyed when he couldn’t measure up.”

"Oh," Rin said, gaze dropping to the floor and mood plummeting with it, once again feeling the otherness he'd almost been able to suppress.

The blue fire, new dangerous features that sometimes grew without his conscious decision, and a deadly enemy in Satan weren't enough. Now he had to add demonic hormone issues where he'd kill anything weaker than him in a berserk state until he wore out enough or a stronger demon got to him first.

A claw came to flick his nose, startling him from the heavy turn to his thoughts as Rin hissed in shock up at Mephisto where they sat on bean bag chairs in front of a screen.

"You're overthinking things, it's really not too bad and it's not like you'll catch any human diseases, so relax and enjoy yourself, hmm?"

"Bastard," Rin grumbled, but he didn't like overthinking things in the first place and took the offered game controller in the newest efforts to distract himself from the fact that in some odd hours he'd be…

Right, back to mindless video games.

Which, actually, weren't so bad to get lost in. Rin smiled, getting out his frustrations in the fast-paced violent fighting game and listening to Mephisto becoming more animated the closer he came to winning each round.

Amaimon was a calm presence beside him, the warmth from his body reaching where his shoulder leant back near Rin while he amused himself with a borrowed manga.

Time passed.

His tail twitched at his feet, reacting to his mood as Rin fell into the rhythm of the game.

He wiggled in place, annoyed that his palms had begun to sweat on the controller.

Another hiss escaped him when Mephisto got in a good combo and won their newest bout.

-And then he growled, low and deep when Amaimon trailed his fingers down his tail through the robe, Rin's gaze flashing with blue flames at the disturbance. He'd been about to win that match, and Amaimon had cost him it.

"Ah, it seems, Amaimon, you'll have to leave him to me this time, he's quite wound up," came the mocking- always _mocking_\- words from Mephisto.

Rin's grip tightened around the controller, hearing a creak of cheap plastic at the force. His growl leapt an octave when Mephisto moved into his space.

Mephisto sighed, snapping his fingers and vanishing both their robes and the game system while Rin turned to slash with black claws at Amaimon when he still hadn't left his tail alone.

"Amaimon, we can't both play with fire, someone's got to be smart about this- and you've already had your fun today," Mephisto said when Amaimon pouted at them from the corner he'd vanished into.

The absence left Rin to crouch on the cushion he'd been laying on, shoulders hunched as he prepared to attack-

-Only to shout when Mephisto flipped him onto his back, throwing his balance as he ended up staring at Amaimon upside-down and snarling in confusion.

"None of that," Mephisto said, beaming down at his furious expression, "your unique heritage has made this much more difficult than it has to be, but, fortunately, I have some experience in dealing with a more powerful demon's heat."

Rin's hands were pinned at the wrists, spine arched close to discomfort over the edge of the cushion by Mephisto.

He didn't let up his growls, snapping his fangs in a sharp clack when Mephisto straddled his hips and bowed to murmur in his now long, pointed ear where it wedged against the carpet.

"You won't be killing me just yet, Rin, you'll have to get stronger before you can attempt it- something to remember for your next heat."

Hips ground down onto his, a relentless and slow torture that had Rin throwing his head back and bucking up to meet Mephisto. A nip of needle-tip fangs at his ear had him trying to bite the throat in his view.

When he failed that, Rin flared his fire, baring teeth in a wide grin at the pained growl he got in return before Mephisto tightened his grip on his wrists until the bones ground together.

Rin cried out, flames vanishing to leave Mephisto sneering down at him, still smoldering, with wisps of blue fire singeing the skin of his face and throwing gaunt shadows until he looked like a grinning skull.

“Do you want relief or not, Rin?” The mocking words came again and Rin howled his rage, fangs fully extended in his mouth even as he ached for the relief Mephisto promised to provide.

“It seems you require a little more wooing.”

A hand found his length, sliding in a firm grip that Rin hissed to feel, jaw dropping at the shock of pleasure and body whipcord-tense before he slumped in Mephisto’s hold with a whine. The whine choked in his mouth as a thumb toyed with his slit, overstimulating him until he began to struggle anew to escape the sensation.

But his rage had faded out, in its place, the heat that had been the source of it took the other path to find release and Rin sobbed under Mephisto’s torment. His body shook at the pleased hum from Mephisto when he submitted, Rin’s hips twitching where they were trapped between unmoving legs.

Finally, just as he was on the brink, the torment stopped. Rin panted, trying to get Mephisto’s hand back now that it had left him, needing the slick friction that vanished without warning.

His whimpered sounds of complaints turned into a moan when Mephisto traced a claw to his entrance and shifted positions to allow him to spread his legs. The clawed finger pushed in, a maddeningly slow pace that never became enough, even with the addition of more fingers.

“_Mephisto_,” Rin found the word, each syllable of Mephisto’s name pulled one after another on a taut string to beg for more.

“Oh good, I was wondering if it would only be Amaimon getting the special treat of his name from your lips, Rin.”

He tried to say the name again, a garbled jumbled of syllables that scattered in his mind and failed on a tongue that felt too thick in his mouth, too long where it lolled over his lips.

Mephisto removed his fingers. Rin spread his legs until they ached, tail snapping like a live-wire to the side in rapt anticipation of the next step.

Rin found his tongue captured by a hot mouth over his instead, Mephisto leaning until their chests rubbed together, covering him in a heavy blanket with his larger body and grinding their lengths against each other.

The kiss swept his mind under. A lone thought breaching the surface that it was his first somehow added to the intensity and sent heat straight down to add yet more pre-come to the mess smearing over his stomach.

When Mephisto pulled away, trailing a line of saliva between their lips, Rin whined at the loss, wanting those lips back on his, wanted them stealing his breath away.

But Mephisto just smiled down, acid-green eyes glinting in the bright lights of the screen and merciless.

Maybe-

Amaimon. Rin bent his head back to search for his only other option and, when he saw him still watching from the corner he’d claimed, opened his mouth to plead.

“Amai- _mmn_,” he gasped, arching in a harsh angle, breath cutting off when his neck bent where he pushed it to the floor.

Mephisto shoved in another inch, the earlier preparation having healed during their kiss so that Mephisto’s entry was only assisted by the slick there.

“You- hah- heard him, Amaimon, come give his mouth something to do."

In another instant, a shadow covered the flickers of the screen where Amaimon blocked it, haloed in the light.

Gold eyes glowed, eclipsing everything else as Amaimon leaned down to press their lips together.

He kissed like a fight. Every breath taken by Rin consumed as Amaimon bit until he swallowed not just air, but blood too.

Rin’s heart slammed to his ribcage, a wild beat thrown by the way Amaimon devoured him and Mephisto fucked into his body.

Existence narrowed down to the tripwire that Rin became between the forces at both ends, balanced precariously on the space across two mountains.

His legs ended up hiked over Mephisto’s shoulders, the angle giving him access to that point inside Rin that shattered his mind apart as he cried out into Amaimon’s mouth.

Amaimon took that too, greedy as he conquered every part of Rin that Mephisto didn’t already have.

It couldn’t last, Rin came against his chest, smatters of his release reaching his and Amaimon’s faces while Mephisto gasped when he clenched around him, movements somehow growing even more forceful until Amaimon had to support Rin’s head in his lap.

The shift gave Mephisto room to lean down and sink his fangs into Rin’s shoulder with a snarl that stuttered his heart to hear until it became a groan when Mephisto came with a bone deep shudder inside him.

Claws clamped to his thighs by Mephisto kept Rin immobile, caught in his contorted position. Not that he even wanted or could move, body limp and mind blissed out so that he was only aware of the fangs in his skin and that his heat was just from exertion now.

A tapered tongue drew a wet line over his cheek, followed by cool relief when Amaimon’s breath puffed against it as he cleaned Rin. The gentle action brought a soft mewl from Rin, leaning his face into the touch and trying to reach him with numbed arms to bring him closer.

Scrunched brows met his attempts as if Amaimon couldn’t understand what he asked for when he pulled back to look down at Rin.

The confusion and Rin’s efforts got Mephisto’s attention, fangs dislodging in a slow slide as they reverted back to their usual length. He chuckled into the healing indents, his own tongue coming out to clear the red he hadn’t already gathered.

“It appears he’s especially affectionate, Amaimon, don’t leave him wanting, now.”

Affectionate? Rin just needed Amaimon’s mouth back on his.

He purred, staring through half-closed lids as Amaimon cocked his head before giving into his request.

This time, Amaimon guided him through a careful kiss, clawed finger-tips resting in delicate points to his jaw like he wasn’t sure what Rin expected of him but would try anyway.

Rin managed to get his arms working, bringing them to fist in Amaimon’s hair and perfectly happy to stay kissing him forever.

About halfway through that thought, Rin came back online, purr dying in his chest and hands gripping Amaimon’s hair in his frozen indecision.

Another chuckle came from Mephisto, his tongue laving in a wide sweep over Rin's fluttering pulse and up his jaw. The path he took drew Rin from the minor panic he’d fallen in, mind blanking as Amaimon broke from him to meet Mephisto.

His breath stopped in his lungs, mouth gaping as he watched Mephisto claim Amaimon above him, their tongues winding together and faces covered in _his_ blood and release.

Why were they-?

Swallowing made Rin aware of his suddenly dry throat, clicking when he fell further into the sight and drinking it in, imprinting it in his memory.

It was the hormones, had to be. The argument sounded weak even to Rin.

Because the remembered taste and feel of the two demons above him still lingered in his mouth. He flicked the tip of his tongue to his lips, eyes wide as Mephisto pulled back with a satisfied smile at the flush now staining Amaimon’s cheeks.

Too much, it was too much to think about then. Rin had to have time to process what was the heat and what was his actual, true self.

“I want a shower.”

Two pairs of eyes once again blinked down at him before Mephisto, appraising expression on his face, drew back to set Rin’s legs down and pull out.

“Very well, Amaimon will take you there,” he said as he rose, snapping to clean and clothe himself in a new robe.

Rin rubbed at his hips, trying not to think about why they ached as they healed from the strain they’d been under.

Rolling out of the uncomfortable position only resulted in Rin feeling the absence of the solid heat from Amaimon’s lap that lingered where his head had rested.

Amaimon led the way this time, still refusing to bother with clothes or cleaning himself and really not helping Rin find clarity. Reason number one for his current problem with Amaimon being the green tail that swayed behind him as he walked, not something Rin ever considered he might be distracted by and yet another thing to think about later.

“Wait,” Rin called, confusion at a sudden realization hitting him as Amaimon glanced back as if wondering what the hold-up was now, “why didn’t you just teleport us to the bathroom?”

A long sigh met his words as Amaimon crossed his arms, “you said to ask before- you might want to walk. We’re walking.”

Rin couldn’t keep the shock from his face, claws scratching to his thighs where they hung at his sides as he tried to compute what could be real consideration from a demon who, up until now, had seemed cold, withdrawn, and faintly condescending.

Irritation started to draw lines in Amaimon’s face so Rin hurried to soothe him- besides, better to encourage good behavior or risk dealing with future violations.

“Thanks, Amaimon, we can keep going,” Rin said, smiling and watching the odd way Amaimon’s expression wiped clear, jerking so Rin once more stared at the back of his head as they continued to the bathroom.

Whatever, Rin would parse the weird non-moods later when he wasn’t trying to ignore the various fluids making his body a sticky mess and really hoping he hadn’t left any traces on the carpeted floor.

They arrived, Amaimon pushing open the door to a palatial bathroom bigger than Rin’s entire dorm room and stepped inside.

He didn’t want to take the time to fill what was basically a small pool that made up the raised tub in the center, so Rin searched until he found the shower and a towel rack.

Grabbing the surprisingly unscented soap, Rin started for the shower with a cheerful sound at finally getting clean in a way that wasn’t done by snapping fingers.

And heard the click of clawed toes on the tiled floor behind him, stomach dropping as he remembered Amaimon was still there.

“Hey! I’m good for another four hours,” he said, brows twitching as he growled at Amaimon, getting another blank expression for his efforts. “You don’t have to hold my hand to the shower too.”

Would Amaimon even listen to him? He hadn’t in the bed, just making himself comfortable next to Rin.

But, aside from the frown pulling at Amaimon’s lips, and his drooping eyes, Amaimon nodded, turning to leave and raising his hand to snap himself away.

A clench struck in Rin’s chest when he saw Amaimon had actually listened to him- was leaving him to shower in peace, made Rin almost call him back, a sense of guilt he had no clue why he should feel at all permeating out.

Maybe it would be okay if he let him join, the shower was big enough, and it wasn’t like he seemed all that interested in messing with Rin when he wasn’t...

Rin shoved the strange urge down, determined to at least get into the shower before he started panicking.

Which was why, when the snap of Amaimon departing echoed in Rin’s ears sounded, he flinched and hunched his shoulders like he expected an attack.

He wasn’t used to having to think about things! Rin wanted to whine in complaint, glaring into the hot water as he scrubbed until his skin became raw and reddened. The most he’d ever had to deal with was school, fights, and the lack of a job or friends- not demon-related anything!

Having to clean the slick and release from inside him brought red to his skin for an entirely different reason and Rin hurried through the embarrassing process.

Though he did wonder if-

-No. He had just been through four separate heat-induced claimings and he wouldn’t be accidentally inducing another one ahead of schedule because he got curious.

His tail, soaked and covered in soap suds twitched at his feet in the pooling water, giving him a new focus.

It had also gotten dirty and Rin knew how bad the fur could start smelling if he didn’t let the soap from his hair run down it in the shower.

Usually, that level of washing would be enough for Rin. He’d never liked touching his tail because of the one too many bad experiences he’d had with it getting pulled or yanked when he forgot he had it again.

But if Rin had to smell the evidence of his activities any more than necessary he didn’t think he would survive the week. So Rin would be washing his tail.

More of the unscented shampoo went into his hands as Rin worked it into a lather between them before reaching for his tail that rose up on his command.

A thoughtless move later and Rin stroked the lather-covered hand down the length of his tail.

“Ah!”

Rin moaned in surprise, stumbling back into the tiled wall as his hand gripped the tip of his tail where he’d ended at.

He shook in place, eyes widened and jaw dropped open, working soundlessly while he tried to understand where the pleasure winding up his spine had come from.

“No- no way,” he whispered into the pattering drops of water around him, fingers spasming around the length he hadn’t let go of.

Was everything trying to turn him on? Would he never escape his own body?

Without his say, his hand gripped the base of his tail, hesitant as he tried to figure out if he would really go through with his next move.

A vague memory came to him of the last four times he’d been under the haze of the heat- of his tail twining with Amaimon’s, of the way Amaimon had tugged at the base of it just like-

“_Anh- ah- ha_.” Rin’s hips thrust up with the stimulation of the tight bundle of nerves that he dug his thumb into, working his hand down and using the shampoo that hadn’t washed out to prevent the fur being pulled.

Wild-eyed, he snatched the bottle at his feet, pouring more into his hand and going back to stroking his tail in long pulls, a gasp leaving his throat when he accidentally dragged the wrong way against the grain of his fur.

Electric tingles jolted along his nerves, his hand moving faster over his now thrashing tail.

He came with a low cry, hips stuttering before he dropped on trembling legs to the floor of the shower, tail finally laying limp across his lap.

Reality and awareness came back to him in a snap, like he’d been doused with cold water.

“Oh, what the hell?” Rin cursed, glaring into the spray as he leaned back to the tile before closing his eyes and sitting there. “That can’t have been the damn heat, right? There’s no way.”

It couldn’t have been the heat- he’d literally just satisfied the latest bout, like, fifteen minutes ago!

The other option being that it was just him.

“Maybe it is the heat,” Rin said, grimacing and forcing himself to stand to finish the shower and fixing another glare on his tail, “at least you’re clean, dammit.”

Dammit. Rin swore again inwardly, shutting the water off and stepping out to towel off. He’d avoided one curiosity only to get swept up by another- showed how good his self-control was.

Muffled grumbles into the towel took up the rest of his time until he tossed it over the shower bar for a lack of any better idea of where to put it. Then he just had time to feel anger at himself for wasting valuable thinking time in the shower before another realization hit him that had him wanting to bang his head into a wall.

“Clothes! I need clothes!”

How had he forgotten to ask Amaimon for some? Rin cursed the lack of foresight, blaming it on his distracting thoughts about Amaimon in the first place and going back to yank the towel around his hips.

He knotted the ends in place, exiting the shower and shivering at the air-conditioned hall that met him. Goosebumps rose on his skin so Rin let his fire respond, core-heat rising until steam wisped away- one of his favorite new tricks he’d learned.

Anything that hadn’t involved actual flames came easy to him, but the moment he’d tried anything with fire, fear emerged with it to make it flare up in erratic bursts that singed everything into blackened ash. So Rin had avoided his flames, shoving them down and keeping to the safer heat beneath his skin.

And that train of thought wasn’t helping his mood. Rin let a billow of hot air escape his mouth in a huff, stalking down the hall until his steps slowed and he stopped, glancing around.

Where, actually, was he?

A hall he’d never been in greeted his eyes. Rin sniffed trying to find a trail to follow, but, when all he got were old traces of Mephisto and other scents he couldn’t place, Rin gave up.

“Guess I gotta retrace my steps." He sighed, beginning the trudge back the way he’d come from.

A cloud of pink smoke sent him tripping to the ground with a shocked scream, hand coming to press to his rapidly beating heart as he looked up into Mephisto’s peeved face.

“Mephisto!” Rin shouted, hoping the pitch of his voice indicated exactly how not happy he was for the jump-scare.

But green eyes just narrowed, Mephisto reaching to pull him up by his elbow before snapping to bring them away.

“Hey! What the-” Rin tried to get out.

Mephisto held up a finger, expression stony, as he spoke, “do not go down that hall again, Rin.”

“Er, why?” Rin paused, not liking being told what to do but even more not liking the serious way Mephisto appeared then.

“I have already punished Amaimon for leading and then leaving you so close to that part of the manor,” Mephisto said, the word punish making Rin wonder exactly how and why he’d needed to do something like that to Amaimon but didn’t get the chance to ask.

“Belial is sequestered to that side during your heat, you cannot go over there, do you understand, Rin?”

Belial again. But Rin had gotten the point last time and nodded. “Okay, got it, um, where is Amaimon?”

Seeing his acknowledgement, Mephisto changed his demeanor, teasing smile taking over as Rin immediately regretted his question.

“Why, Rin, I didn’t realize you cared so much for Amaimon, are you missing his company already?”

“Bastard,” Rin hissed, stomping around him to the chair a robe had been laid on and exchanging it for his towel, “are you gonna answer or not?”

"He's away licking his wounds and sulking, but he'll be back later," Mephisto said, shrugging and snapping to bring them back to the kitchen.

"Now, I imagine you're hungry, or you will be in a few hours, so why don't we get that out of the way."

Rin sighed at being yanked around and commanded, already missing Amaimon.

But, Mephisto was right. He could already feel the pangs of hunger and knew he only had a few hours before he'd be burning even more energy.

"And lemme guess," Rin said, snorting as he walked to the fridge to see if he could do anything with that glowing purple fish, "you're gonna want something too."

The smirk from Mephisto practically burned into his back as he glared down into the fish's gelatinous eyes.

"Well, I am putting you up in my home- attending your voracious appetite." Rin's tensed shoulders at the blatant insinuation brought a soft laugh from Mephisto before he continued, "and there is, of course, the main and most important reason."

His trailing off made Rin turn to glance at him beneath his bangs as he began preparing the fish.

"What?" Rin asked, a mutter as he waited for more teasing at his expense.

"Your cooking is simply divine, I wouldn't miss it for the world," Mephisto finished, winking at Rin from where he sat at the counter, chin propped on his palm.

"O-oh," Rin stuttered at the unexpected compliment, cheeks heating in a blush that he turned to hide, blurting out a quick thanks.

He managed to make a dinner to be proud of out of the weird demon fish thing, if more of Mephisto's over-the-top moans of pleasure about it meant anything.

Amaimon's absence bothered him for some reason he couldn't explain, the empty third dish sitting on the counter before Rin gave up and put the leftovers in the fridge.

"That's for Amaimon, don't take his portion," Rin ordered a pouting Mephisto, not moving until he agreed.

"Rin, why don't you join me in my office until Amaimon returns to keep an eye on you?"

That sounded incredibly boring to Rin but it wasn't like he had anything else to do, so he nodded, resigning himself to the next snap of Mephisto's fingers.

Another snap, another poof, and Rin wondered if Mephisto ever actually walked anywhere or just teleported.

A different room than Rin had expected greeted his eyes and it took him a bit to figure out that of course Mephisto wouldn’t be taking him to the office at the academy, so the one they were in must be his home office.

This office had been decorated pretty much the same, though Rin didn’t know anything about interior design, the color scheme at least was similar. It just happened to have more random figurines and personal touches than the school office did.

“Take a seat, get comfortable, you’ve got work to do,” Mephisto said, drawing Rin from his examination with his confusing statement.

“What work?”

Mephisto grinned, pointing to a side table where a stack of textbooks and paper sat.

“Your brother was adamant that you have your homework and study materials available during your absence so you wouldn’t fall behind- better get cracking, that looks like a lot,” he said, enjoying the long groan of dismay his words got from Rin.

Rin spent a solid five minutes cursing Yukio out under his breath at the table.

But, with literally nothing else to do, he forced himself to trudge through the long list of material Yukio had provided, knowing his twin would have shoved extra things in there for him because he’d never be able to tell which was required and which was unnecessary.

Then the room became silent. Only the sounds of Rin’s brain melting from his ears and the scratching of Mephisto’s or his pens over paper filled the next span of time.

He turned another page, his mind a haze and nearly slumped into the surface of the table.

Looking at the stack of homework, Rin wondered if he’d even made a dent, imagining the beautiful kindling it would make if he were to accidentally set it on fire.

No, Yukio would just make him do it all over if he did that. Rin sighed, forehead touching the table, the cool surface assuaging a bit of the stress, though not for long, rapidly heating with his body temperature.

His ears twitched when, without the distractions of his own work, the scritching of Mephisto’s pen seemed magnified.

Squinting an eye open to glare at Mephisto only served to darken Rin’s mood. Mephisto looked like he had just started his work, calmly going over another document in his hands and smile smug at whatever he saw on it- who smiled at paperwork?

Fine, he had to finish his crap anyway. Rin crushed a low growl before it could form, snagging another book from the pile and flipping through to the next section with what might have been more force than required.

More time went by, Mephisto continued his work in silence.

Rin threw the book in the done pile, seeing black claws had formed in his irritation. He clicked them to the table beside the next book in the lineup, drawing them over the surface in a slow movement.

It would feel very good to shred something with his claws. Very good.

Scratching again from Mephisto took Rin from his focus on digging his claws into the table and tearing.

He breathed out through his nose, the heat threatening flames as he watched Mephisto work without any sign that he’d noticed Rin at all.

That damn paperwork.

Maybe Rin would start by ripping Mephisto’s work apart and-

Vibrations from the low growls in his chest were almost enough to cover the endless scratching.

It was impossible that Mephisto hadn’t heard him, wasn’t aware of how he’d been staring at him for the last few minutes

Which meant Mephisto was ignoring him in favor of what was on his desk.

Rin wanted his attention away from the damned papers and on him, wanted those green eyes on _him_.

"Mephisto," he said, voice an odd flavor when it left his lips and sibilant, like a snake before it struck.

Finally. Finally, those green eyes met his, gaze rising from the desk as he set his pen down in a click that made Rin smile to hear as it signified an end to Mephisto’s work.

"Ah, that time already, I haven't gotten nearly as much done as I needed to."

More? He wasn’t _done_ yet?

"Forget your damn paperwork," Rin hissed, levering himself off the chair to stalk towards Mephisto.

"Look at me, Mephisto." His command came out guttural, the flash of dark interest it garnered made a purr rumble in his chest.

"You're a demanding one, I see," Mephisto said, skirting around the real issue and sending the heat in Rin’s veins searing throughout his body.

But, despite the command, that gaze slid from his again after a deliberate pause, ratcheting Rin’s fury up another few dangerous levels.

“If you want my attention, Rin, why don’t you come earn it, hmm?”

_What_? Rin let flames burst from his teeth, feeling extended fangs with his now tapered tongue when he swiped it over the sharp ends.

Fine, Mephisto wouldn’t come to him, he would go to Mephisto and _show him_ why he shouldn’t be ignored.

His palms slammed to the desk, making all the little things on it scatter. A shark-grin sliced across his face when that damn pen rolled to drop to the floor.

Still, Mephisto wouldn’t look at him, leaning to rest against his high-backed chair and scratching at his cheek as if in deep thought.

“Mephisto,” Rin crooned false sweetness as he leant forward, tail swaying in restless coils under his robe.

Nothing. The damn demon didn’t even move a muscle to let him know he’d been heard.

Before he could think his impulse through, Rin’s instincts sent him crawling over the desk, robe parting at the slit as he hiked his leg to haul himself up. He kneeled on the documents that had become the bane of his existence, smiling wider and happily brushing them to join the pen on the floor.

Movement from Mephisto had Rin perking up, wondering if he’d succeeded, and licking his lips at what Mephisto might do to him now.

But Mephisto just drew his clawed fingers through his bangs, tucking the longer strands behind a pointed ear and humming as if bored.

Rin would sink his claws into that hair and his fangs into that ear- _then_, he would have Mephisto.

He hopped to sit on the edge of the desk but didn't try playing unnecessary games, too wound up to even consider drawing things out.

So decided, Rin launched himself in a controlled tumble into Mephisto's lap, robe spread around the both of them as he let out a pleased purr at catching his prey.

This close, he could inhale a deep breath, taking in the sweet scent coming off Mephisto until he couldn't smell anything else.

Nuzzling into the crook of Mephisto's neck got Rin even closer to the source. He wiggled to get comfortable, twisting his hips to rub his length against Mephisto's suited stomach.

A slight tensing of the body under his meant his efforts were working. But it still wasn't enough. He'd have to go with his original plan.

One last breath to the underside of Mephisto's jaw-

-Then, he got his claws in that thick hair and sunk his fangs into Mephisto's ear, eliciting a sharp growl as Mephisto _finally_ stopped ignoring him.

"You brat," Mephisto said as he gripped Rin's hair, his other hand digging claws into the jut of his hip bone when Rin just smiled where he licked the healing wounds.

Snapping removed the annoying barriers between the two of them, Rin responding by grinding down on Mephisto's lap, gasping and releasing the ear from his teeth.

He'd already begun leaking slick and pre-come, the added scent of both spurring Rin into erratic jolts of his hips as he chased the pleasure of skin against skin.

Mephisto didn't let him control the pace for long, the hand at his hip guiding him into a quick rhythm that Rin was happy to comply with now that Mephisto had gotten with the program.

It wasn't what he was really after, though- wasn't enough to calm the burning in his gut.

Rin, a slave to his instincts, whipped his tail to wrap around Mephisto's torso, writhing in wild twists while Mephisto shuddered.

Closer, he still wanted to get _closer_.

And he needed Mephisto to kiss him again.

His tongue traced down from the tip of Mephisto's ear in a slow glide, hearing the deep rumble start up from Mephisto when he made his way to his lips.

That first slide of their tongues together had Rin moaning into Mephisto's mouth, eyelids closing without his say and body slumping while he lost himself in the kiss.

The hand at Rin's head tilted it into a better angle while the one at his hip moved to knead the base of his tail until Rin gasped.

"Please, please- a-_ah_!" Rin pled against Mephisto's lips, achingly hard and torn between pressing his length forward into Mephisto's stomach or shoving back into his hand.

Even that simple word took more concentration than Rin could spare and he was reduced to whimpering, forehead falling to Mephisto's shoulder.

He clung to Mephisto, sightless and panting and acutely aware of the finger now running down from his tail to his entrance.

But Mephisto just prolonged the agony, rubbing and teasing Rin into a trembling mess. He'd started palming him to send slick staining his hand and length where it nudged at Rin, a cruel taste of what would come.

Desperate, Rin tried to convince Mephisto to stop, forcing his head up to brush their cheeks together with a plaintive mewl of his name into his ear. He drew his hands down from Mephisto's shoulder blades to his tail, returning the favor and kneading the base.

A hitched breath that became a groan made Rin purr, knowing he'd succeeded.

"Mmm, I'd say you've more than earned this, Rin," Mephisto murmured into his ear, lips touching to Rin's cheek in a soft kiss just as he began preparing him.

That first breach of Mephisto's length into him stole the rest of Rin's mind, only the ache and heat in his body registered at all.

Rin couldn't wait anymore, lifting himself along the length inside him and dropping back down in a fervent pace.

His thighs burned, pushed to the limit as Rin nearly bounced in Mephisto's lap, knees bruised where they dug into the wooden edges of the chair.

Sounds came in a meaningless stream from his mouth, a jumble of gasps and moaned pleas, though he couldn't say what or who he pled to.

Through it all, Mephisto allowed him control of the pace, only keeping his hands in the lightest of holds at his arm and thigh to stop him from falling.

"_Ha-ahh_!" Rin cried out, having just managed to hit the point inside himself and scrambling to find it again.

Anything to get that intense shock to strike.

He clutched the back of Mephisto's head, claws clenched in the short hairs at his neck to bring him to his shoulder, sensing he was close and needing that white hot pain.

Mephisto obliged him.

Fangs bit deep just as Rin found the spot again, tightening around Mephisto as he came until Mephisto took the reins and fucked up into him in quick jerks of his hips.

Warmth pooled inside Rin, Mephisto biting deeper into his muscle and growling his release, hands forcing Rin down as far as he could go and holding there until he finished.

Rin stared at the ceiling, uncomprehending, panting and shaking like he'd been electrocuted.

Slowly, shapes began to have meaning again. Sounds came next, their breaths and thudding hearts mingled so that Rin couldn't tell one from the other.

And finally the way their scents mixed in the air had Rin sucking in gasping lungfuls, needing to take in the way Mephisto's claim on him settled on his tongue.

His tail twitched, twining tighter around Mephisto as Rin fell forward, a flinch resulting when it jarred the fangs sunk into him but Rin was unable to stop.

He was utterly spent.

Boneless and numbed limbs draped over the body he lay on, letting the calming heartbeat and pulse in his ear lull him too.

When Mephisto brought his hand from Rin's thigh to scrape the sweat-drenched hair away from his ears and cheeks, Rin didn't have the energy to startle, though his heart skipped.

Mephisto was- he was _caressing_ him, gentle scratches through his hair and even going so far as to massage the base of his skull.

Why was he-?

Stop, don't overthink it.

But it did feel really nice.

Another purr started up in Rin's chest, contentment pouring through him in soothing waves as he drifted in the afterglow.

"You can't fall asleep here, Rin," came the soft reminder, though with a hint of an edge to it that warned Rin Mephisto was about to tease him, "unless you'd prefer to stay in my lap until your next cycle begins."

Normally, Rin would at least be sending Mephisto a dirty look for that inane suggestion, but he was still too blissed out to care about it right then.

He did crack an eye open to weakly glare at the back of the chair.

"I wanna go to bed now," he mumbled jaw beginning to hurt from the pressure of keeping his weight on it and the liquid inside him cooling where it leaked out around Mephisto, becoming uncomfortable.

A jaw-cracking yawn decided it for him, wanting, in this one case, for Mephisto to snap him clean and into bed already.

Lips mouthing at the now-healed bite answered him instead, not that Rin was in any particular hurry to move.

"Very well, Rin." The snap came, Rin cleaned and robed again, carried in Mephisto's arms until he leant to place him under the covers.

Rin turned to bury his face in the pillows, waiting for Mephisto to disappear again and frowning in confusion when he didn't.

"What, no request for a kiss goodnight?"

A what goodnight? Rin blinked, turning back over to look up at Mephisto's face.

It felt like a test.

"Would you even give me one if I asked?"

Mephisto let a slow smile scrawl its way over the indecipherable expression he'd just been wearing.

Then, before Rin could react, Mephisto bowed over him, taking his mouth with his in an unhurried kiss.

"Goodnight, Rin, I'll see you tomorrow- or in four hours time, unless Amaimon has decided he's done sulking."

There wasn't anything Rin could think to respond to the strange kiss that made his lips buzz like Mephisto was still touching them except a goodnight with barely enough strength to reach his ears.

Then Rin was alone in the room, the bed feeling too big with just one body in it.

Sleep took him under so he didn't have to worry about anything, especially not that he might actually be missing another body beside his.

* * *

Rin tried to hide a sigh from where he lounged on the couch in Mephisto's office next to Amaimon, who'd entertained himself with another manga.

If this was what Mephisto did all day, mindless paperwork, Rin didn't know how he managed eternity.

"Okay, that's it!" Rin bolted up, tossing the handheld game to the cushion and meeting the raised brow from Mephisto.

"I'm gonna go stir crazy if I don't do something that isn't sleep, eat, or play games- and _don't_ bring up the other thing, dammit, you know that's not what I'm talking about, Mephisto," Rin finished his tirade, huffing as he waited for Mephisto to respond, hopefully with something to do.

A cheerful ringing from Mephisto's phone interrupted him as he'd been about to speak. Rin grumbled and dropped back down to the couch.

He glanced at Amaimon, seeing an odd expression on his face, almost anticipatory, and wondered if he had any ideas to get rid of Rin's boredom.

They'd have to wait until after whatever the call was first. Rin sighed and hung his head over the back of the couch.

"Hello, Angel, what a pleasant surprise, the lofty Paladin giving me a call- congratulations on that promotion, by the way. What ever could the occasion be?"

Rin knew by this point in the week how to see when Mephisto was being a deliberate ass, and whoever this Angel person was had to be fuming on the other end of the line.

Wait, did he say Paladin? Rin jerked his head up, antsy with the need to know who had become the new strongest exorcist and how they measured up to his dad.

An irritated expression on Mephisto's face told him something was wrong.

"Ah, you really do have awful timing, I've got something on my hands that requires my utmost attention-"

There, his eyes slid to Rin's, letting him know _he_ was the thing that required Mephisto's utmost attention and making Rin scowl to cover a blush.

"-And I really can't leave- oh, I see, an order from the Grigori, you say?"

That gaze flicked to Amaimon before Mephisto hid a sigh, "well if _they're_ the ones requesting me I can hardly decline, I'll be there shortly."

"Ciao, Angel," came the mocking goodbye from Mephisto, though from the click on the other end, it had gone unanswered.

"You're leaving?" Rin blurted out before Mephisto could speak, wondering what that meant for him and when he'd be back.

Instead of the teasing rejoinder Rin expected from him, Mephisto cast a peeved look at the far wall and sighed.

"Unfortunately yes, the Grigori call and I answer- part of the agreement I have with them currently."

Now Rin sighed too, "so I'm stuck in here, bored out of my mind still, great."

"It can't be helped, you and Amaimon will just have to entertain yourselves without me until I return, I'm afraid," Mephisto said with an uncaring shrug.

A gleam in his eyes warned Rin he wouldn't like his next sentence.

"You could work on the new material your brother assigned you."

Rin glared, giving it the consideration it deserved, which was none.

"No? Ah well, that was my suggestion, I may be back tonight or tomorrow, don't destroy my house before then."

And with that, he was gone, leaving Rin alone in a silent room with Amaimon.

"Please tell me you have something better for me to do than homework," Rin said, head lolling from sheer boredom to gaze hopefully at Amaimon.

He blinked, seeing luminous gold eyes staring at him while Amaimon chewed his clawed thumb.

"Fight me."

"Er, what?" Rin said after coming up blank.

Amaimon dropped his thumb from his mouth, palms pressed flat to the couch cushion between them as he leaned forward, expression the most animated Rin had ever seen.

"Fight me, please!"

Enthusiastic, Amaimon was downright enthusiastic about fighting Rin and-

-And now that he started thinking about it, the idea warmed on him, _anything_ to get moving.

"Okay, sure, but where?" Rin said, his hopes of getting out of the manor crushed because where even were they supposed to fight? The kitchen?

"Yes!" Amaimon cheered, startling Rin from trying to figure out which room they would get in trouble for the least for destroying.

"Let me take us there," Amaimon said, nearly vibrating where he sat and hand raised to snap them to where he had in mind.

"Yeah, let's go." Rin nodded and the snap came, an unfamiliar room revealing itself in the next moment.

"Where is this?" He asked, taking in the wide concrete and brick enclosed room.

"Underneath the Academy, no one will know we're here," Amaimon explained, already stalking around the space like a tiger in a cage, waiting for Rin.

Rin shook himself out, sizing Amaimon up and wondering how strong the seventh in Gehenna could be.

His wide grin met the one formed on Amaimon's face.

"Let's go."

A sound like a sonic boom cracked across the floor.

Amaimon's afterimage faded as Rin flew into the far wall, mind trying to catch up to what had just happened.

But his body reacted for him, relying on instinct to launch himself back to where Amaimon had stopped after his punch and returning with one of his own.

Their claws met, drawing bright red from the slashes scored while Rin, during a moment of free fall, laughed in wild abandon.

Had he ever felt so alive before? He threw Amaimon from a deadlock they'd entered, chasing after him and tackling him to the ground.

When it only resulted in Amaimon reversing their positions, Rin didn't even mind, jerking an elbow into Amaimon's middle and getting a grunt of pain for his efforts.

He hadn't even used his flames yet and it was already the most fun he'd had in months!

Which was why, sometime later, when Rin felt the stirrings of another sort of heat in his gut, he was disappointed.

Groaning where his most recent meeting with Amaimon had ended in turn with him meeting the floor, Rin lay there, staring at the ceiling and pouting.

"Why did you stop?" Amaimon called before jumping to settle at his feet, mirroring his pout.

"I hate this," Rin glared at nothing, hoping, if he ignored it, maybe this time it wouldn't over take him, "I just want to be able to go more than four hours without losing my mind."

His complaint got him a considering expression and crossed arms from Amaimon.

"Five hours."

Another non-sequitur from Amaimon Rin had to think about, harder to do when his damn instincts kept reminding him with increasing insistence that he was already on the floor and Amaimon smelled great after their exertions.

"You went past the four hour mark, and you're still rational now- enough to recognize it's begun," Amaimon said when he realized what Rin's silence meant.

"You mean it's ending soon?" Rin propped himself up to meet Amaimon where he kneeled over him, too happy to be embarrassed about how excited just being near Amaimon made him already.

The nod Amaimon sent him had Rin smiling, though his ears buzzed as his concentration narrowed on the way deft claws parted his robe.

While not the location he ever thought he'd be doing something like this in, it was kinda nice that Amaimon always took his time removing their clothes and didn't snap them away like Mephisto did.

Especially because Rin had grown to appreciate watching the way the layers of Amaimon's clothes fell from his body.

Rin licked at his lips, wanting to get his fangs into the nearest section of skin he could reach on Amaimon as the adrenaline remaining from the fight frayed his nerves.

When Amaimon claimed him this time, Rin clung to him, more of his awareness there than he'd had all week.

It made him cling tighter, heart pounding as a thought breached the heat.

What would happen when the week ended?

He dragged Amaimon down into a kiss to forget, focusing on the present instead of whether he'd ever see Amaimon again.

Later, panting beneath Amaimon on the newly stained concrete floor, Rin decided he would invite him into the shower with him after they got back to Mephisto's.

So he did, not hiding the smile when Amaimon, after a startled pause, nodded and joined him under the hot spray.

The rest of the day went in a blur, Rin struggling through his homework as Amaimon entertained himself in a steady stream of suckers and manga, the clicking when he rolled the suckers to his teeth no longer bothering Rin to hear.

Going to bed that night, close, but not touching, so that Rin could reach out and find Amaimon if he wanted to, Rin fell into a restless sleep.

* * *

Hot. He was so hot.

Why?

Rin reached out a hand, whimpering when it touched a cold spot instead of the body that was supposed to be there.

Where?

His eyes opened, glazed but searching for Amaimon.

A sob loosened from his throat when sight confirmed his other senses

Amaimon was gone, had been for some time.

Oh god, Rin curled into a trembling ball, slick making a mess on the sheets he twisted in.

He hadn't felt this bad since those first few days, why was it back?

And where was _Amaimon_?

The absence of both Amaimon and Mephisto had Rin moaning, both in fear and because he'd started palming himself to try taking the edge off.

When all it succeeded in doing was to make the heat inside him flare, Rin gave up, shaking on the bed.

Instincts drove him from the room, stumbling and crying out when his robe itched at his oversensitized skin.

"_Amaimon_," Rin called out, voice cracking as it turned into a distraught keen when Amaimon failed to appear.

Nothing. The halls seemed darker and colder than he'd ever seen them before, his steps taking him along old scent trails.

Each time a trail faded and forced Rin to follow a new one, his cries grew more desperate.

Wait. Rin froze, using the wall to hold himself up.

Maybe Amaimon was on the other side of the manor?

And if he wasn't, Rin licked at his chapped lips with a long tongue, vision narrowed as if he had blinders on.

If Amaimon wasn't there, he'd scented someone else.

Someone who could take the burning ache from inside away.

New energy, spawned from thoughts of stopping the maddening heat, propelled him back to the hall someone had told him to avoid.

Why would he do that when the possible answer to his needs hid there?

Rin blinked, finding himself faced with a solid door. When he pushed on it, it resisted.

Someone had locked it. Rin set the door on fire, strange smile lighting on his face to see the blue flames fill the hall.

He pushed again, this time tinders fell at his feet to smolder in the carpet.

_There_. Rin could smell a demon in the room, stalking towards it to see if it would measure up or he would have to find another.

Slit pupiled eyes stared back at him from the dark, reflecting the cold light from the moon outside the window.

Another step, the demon stepped back, then flinched as if pulled on harsh strings.

Good, now he would tear him apart.

Slowly, as if resisting, the demon moved forward into the light coming through the window.

But-

No.

_No_!

It wasn't Amaimon or Mephisto. Rin felt horror slice some of the haze from his mind, fighting viciously with his own writhing instincts to stop from going towards who must be Belial.

He needed Amaimon and Mephisto!

Glass shattered around him as he threw himself away from Belial, frantic as he took in gulping breaths to search for the sweet scents he'd come to know.

Just like the long ago day on campus when he'd found Mephisto, Rin caught Amaimon's scent, though it seemed so far away.

Didn't matter, he'd track him down, _find him_-

-And Amaimon would make it all better.

The edges of Academy Town glowed in his senses. He had never noticed before.

Something cold slid down his spine when he blew straight through the barrier. Rin didn't care.

Amaimon was out there in the empty lands surrounding the city.

Rin darted over rooftops until they spaced out farther than he could jump.

A terrible screeching overhead spurred him on as the scents of thousands of demons- the ones that always circled the Academy- converged on his trail.

Rin only had one thought going in a mantra in his head.

_Amaimon Amaimon Amaimon_

Even if every step tore him in two directions- the demons answering his body's call, and the faint scent he followed amongst so many others.

Where was he, why was he so far away? Rin crashed to the ground, shoved into the gravel road he'd ran on by a massive clawed hand.

The demon it belonged to roared its triumph, pressing until Rin's cheek fractured and he screamed.

Flames seared into existence, then it was the demon screaming as Rin incinerated it into oblivion.

It hurt, it hurt! He hauled himself from the road, grit sticking to his bloodied skin as he ran before the next demon could appear.

Because, for a moment, being weighted down under the massive demon had sent a surge of lust to blacken his mind.

Scenery flashed by in a confusing whirl of shadows and shifting darkness, Rin's senses further thrown by the cacophony overhead.

Territory he didn't recognize, never having traveled this far in his life, had tears making wet tracks on his face.

To one side, the crash of waves off a rocky shore, to his other, rougher and rougher terrain that ate at the signs of civilization until, at the dead end of the gravel road, Rin leapt an under construction sign and left humanity behind entirely.

His every ragged breath shattered from his lungs, bare feet torn to shreds and healed over and over, numbed by the frantic pulse pounding on his mind to stop, turn and face the horde that promised an end to his suffering.

But Amaimon's scent had grown stronger, though Rin still couldn't see him, couldn't find where he'd gone.

"Amaimon!" Rin screamed the name, wailing with the terror and need coursing through him and so distracted by it he missed the jutting stone in his way.

Uncontrolled sobs were the only thing Rin could manage when he landed, body spent in trying to resist itself.

The demons drew nearer, their multitudinous cries sending Rin quivering in anticipation before disgust made him shrink in on himself on the ground.

"_No_," Rin moaned the word out, vision blurred so all he could see were the first, quickest, of the demons to land and bolt to his position

They weren't good enough, were too weak.

A sick grin curled over his bared fangs while the demons burned.

His mind came back somewhat at the energy expenditure. Rin gasped, surrounded by flames and the stinking smell of burnt flesh.

"Amaimon," he whimpered into the dust, trying to force his limbs to cooperate, tail curling around himself in a pitiful attempt at comfort.

It only served to send him arching and scrabbling at the ground when his already sensitive tail jerked in place, long strands at the end caught on a thorny plant.

Another demon, this one slithering on a snake's tail over a mounded boulder, had its human face warped by delirious excitement.

Rin shook against the ground.

Or was it the ground that shook against Rin?

Claws like stilettos grabbed his tail, the Naga demon dragging him towards it while Rin gagged on another scream.

Pain stole his awareness, the grip on his tail excruciating, bending it too far until the bones cracked.

Then they broke.

"_Ahhhhhh_!"

_Help me, please- help me help me help me!_

A quake like the entire earth was devastated stopped everything.

One moment, Rin filled the air with his pain, the next, warm blood splattered to his body, soaking the robe he wore.

When he could open his eyes, nothing remained of the demon that had caught him, in its place stood the hunched form of Amaimon.

A thick tail swept the dirt beneath massive clawed hands like a reptile's that hung at Amaimon's panting flanks

"Amai- Amai-" Rin couldn't get the name out, chest hitching at the electric aftershocks and whimpering when he caught sight of his damaged tail.

But his name from Rin's lips had Amaimon wrenching his head around, fangs serrated wedges and bestial, a furious look in his eyes.

Two green horns with red spirals flowed back from Amaimon's crown to complete the picture that stood over the exploded body of the demon now staining Rin with its blood.

He'd come for him, Amaimon had found him!

"A- _Amaimon_," Rin cried the only word he could seem to manage, tears bubbling up to wash the dust into muddy tracks down his skin as he tried to crawl to Amaimon.

The scent he'd followed just a trace of now filled his senses, a balm on the strain his mind and body were under.

A gong of a clock echoed in the night, jolting Rin where he lay and making Amaimon freeze in place.

Gilded doors appeared like a mirage in the sky, opening to let a figure in white though before shutting and vanishing.

Rin's lips parted around a long keen when he recognized Mephisto, digging his claws into the dirt.

Mephisto landed next to them, and Rin realized his body vibrated with utter fury.

All of it directed at Amaimon.

"Samael, I-"

Amaimon tried to speak, eyes wide and form cowering.

He didn't, Mephisto's hand through his chest stopped him.

"I," Mephisto's words shivered out of him, lips trembling on them and eyes glowing with a cold light as he stared down at Amaimon's body heaving around his arm, "gave you _one_ order, Amaimon. You failed me."

No.

Mephisto raised his other hand, poised to stab straight through Amaimon's head.

_No_.

"No!" Rin shouted, launching to tackle Amaimon from Mephisto's hold, landing on the hard ground and curling into a protective ball over his body.

"Please please please please- no, please no!"

Blood warmed Rin's palm where he clutched it over the hole in Amaimon's chest, his own body wildly tipping between extremes as he pled with Mephisto.

Green eyes bore down into his, that fury that had been focused on Amaimon now turned to him for interfering.

"_Mephisto_," Rin spoke the name like a prayer, one to a cold god.

More demons dropped into their peripherals, the next wave to find Rin.

A snarl tore through the night from Mephisto's mouth just as he slashed with his hand to tear through the demons and ending with him huffing, victory calming some of his ire.

The rest, Rin's whispered pleas soaked up.

Whatever monster grew at Mephisto's core, sank back into him, held once more under his human facade.

He took a long breath in, held it, and released, and, when his gaze met Rin's again, it was with a face he recognized.

"It's okay now, Rin, he's safe, you're safe now."

Hands, now the normal black clawed ones Rin had grown so familiar with, came up to rest at his forearm in a gentle touch.

"It's okay, Rin," Amaimon murmured, heartbeat firm under Rin's ear and the hole in his chest closing in steady inches.

Rin dropped his head, still shaking, but this time in sheer relief as Amaimon used his other hand to card through his hair.

But with that relief came the resurgence of the reason Rin had ended up in that position in the first place.

Now, surrounded by the two sweet scents he'd been searching for, Rin couldn't stop the instincts that demanded they be met.

Not when he'd held them off as long as he had.

"Help, it hurts, it _hurts_," Rin jerked his gaze up to Mephisto's again, begging for a release from his torture.

Something softened in Mephisto's eyes, he held out his hand. "Come here, Rin."

The simple command had Rin rising on wobbling legs, torn robe dragging behind him on the ground as he collapsed in Mephisto's now opened arms.

His snap cleared Rin's clothes along with the drying blood and debris to leave him clean of everything but the new slick seeping from his entrance.

Then it was just Mephisto's white suit, the fabric catching under Rin's hands where he gripped.

Behind them, Amaimon rose, head tossing as he waited for Mephisto's orders, the earlier violence between them forgotten.

"Please take care of those beasts while I tend to this one, Amaimon, and we'll discuss what happened later," came the command.

Heat buffeted a howling storm in Rin's mind, controlling his movements and sending him to drag furrows into Mephisto, red blooming on the stark white.

Amaimon shot a glare to them, though it was weak after the punishment he'd gone through, "only until he's finished with you, then it's my turn."

"Yes- ah! Yes, you'll have your fun too, Amaimon, if he allows it, and if you can take out the trash before he's satisfied himself," Mephisto said, panting as Rin moaned against his neck where he'd bitten and ground down on his leg with increasingly desperate movements.

Rin was barely aware of Amaimon turning to face the swarm of approaching demons drawn by his heat. His focus was on getting through all the layers of Mephisto's damn suit.

He'd never let him do this before, Rin thought when a button popped off after a too sharp tug.

Always, Mephisto made sure to remove his clothes so they wouldn't get dirty.

Why?

Stopping himself took herculean effort, Rin shoving his fist to sink his fangs into his knuckles to do it and whining at the pain.

"Shh, Rin, none of that," Mephisto hushed, pulling his hand from his mouth and pressing it to his chest. "You're fighting your instincts to destroy, I'm willing to sacrifice this suit if it means you don't try to disembowel me later."

Did he mean?

A wry smile tugged at Mephisto's face, "go on, give in, Rin."

Give in. The words throbbed in his head, welling up like the lines of blood that followed his claws down Mephisto's torso.

His tongue found those lines soon after while he tore the suit to ribbons, ripping it further to expose the skin beneath and scraping his fangs there.

Mephisto's hand at the back of his head, pressing him closer, had Rin muffling a moan into his stomach.

More red stained his face, his teeth finding purchase and sinking in while a hissed breath only encouraged him further.

The thought of biting even deeper, of seeing Mephisto laid out on the ground in front of him made Rin jerk his mouth away, reaching instead to pull the fabric from Mephisto's body.

White strips fluttered down around their legs with each wrench of Rin's hands until Mephisto stood bared before him, allowing him control of their direction.

He grabbed Mephisto's hand, bringing it to his face to nuzzle into it and breathing at his wrist to take in the scent, eyes closing.

Fingers uncurled to cup his cheek. He was ready.

Rin slid along Mephisto's body, rutting against him with his eyes still closed as consciousness narrowed to all the points where they met.

Around them, the sounds of the earth screaming nearly covered the screams of the demons Amaimon slaughtered, keeping them at bay.

Pleasure had him riding the edge, just being near Mephisto not enough, until weakness sapped the strength from his bones, leaving him hanging from Mephisto's arms and unable to orientate himself for the next step.

Vision blurring with tears, Rin tried to speak, either Mephisto's name or another plea.

A whirl of movement later and Rin felt Mephisto press his length up along his entrance, a hot brand Rin shoved back to.

Like this, head held by his jaw to Mephisto's neck, Rin could see the encroaching horde.

And he could see the way Amaimon decimated them with each monstrous display of power.

Power- strength that drove the instincts in Rin into a frenzy to see while Mephisto chuckled at his ear.

The other hand that Mephisto had held to the taut plane of his stomach trailed down to pump his length, shocking a moan from Rin.

"I don't know why or how this happened," Mephisto said, voice low and full of wicked intent that sent Rin quivering in his hold, "but he does make a beautiful sight, slaughtering those lesser beasts, doesn't he, Rin?"

Beautiful? Rin watched Amaimon draw a line of gore through demons who didn't know they'd died until they fell in pieces to the earth.

He wanted Amaimon to murder them all, wanted him to emerge a bloody god off the battle field to claim him amongst the rot and ruin.

Beautiful, to describe Amaimon, was too tame.

"Hmm, did you know, Rin," Mephisto said when he didn't respond, struck silent by Amaimon, "that your pupils become warped blue flames when you're particularly demonic?"

No, he hadn't. It wasn't important.

What was important was the tail he'd twined with his and the length he thrust back against even as he tried to push into Mephisto's hand where it toyed with him in leisurely strokes.

"Let's make a wager, Rin," Mephisto said, tone conversational.

A _what_?

"If Amaimon can destroy all those demons before I've come, I will let him have you."

Oh god. Rin whimpered at the thought.

"But if I come before then, if even one demon remains," Mephisto licked at the shell of his ear, Rin could feel the grin there, "if that should happen, then-"

Wait.

"I want Amaimon," Rin cut in, snarl twisting his words and voice into an unrecognizable pitch, "I get him."

Mephisto froze at his back, stopping his touches and not even breathing.

"This," the words from Mephisto came out hesitant, careful, as if he chewed something over, "does not sound like a heat talking."

Rin growled, it rumbled through him into Mephisto.

He talked too much. Rin reached up, fisting his claws into Mephisto's hair and yanking him back to expose his neck so he could let the points of his fangs just needle with implied threat.

"I want Amaimon," he snarled into the column that moved with Mephisto’s swallow. Cold sweat had broken out on the skin Rin pressed his teeth to. He smiled to sense the unease in Mephisto.

Mephisto was able to recover while Rin’s attention drew to the way Amaimon hurled a ridge of stone into the center-mass of the demon horde.

"You poor creature," Mephisto said instead as he splayed his hand over the swell of Rin's ass where slick still coated him, "at war with your own body, it's really no wonder Amaimon couldn't have foreseen this, no one could have."

Another non answer Rin couldn’t understand. Mephisto didn’t explain further, raising his other hand to cup Rin’s jaw even when it made Rin bite harder to his throat.

The action allowed Rin to feel the vibrations when Mephisto spoke.

"But you're not quite there yet, there's still a little left of your heat to deal with before we can begin handling your next problem."

So saying, he plunged a finger into Rin, keeping him in place as he stretched him and accepting the retribution of Rin breaking skin with his fangs where he still held Mephisto’s throat captive.

“Do you accept my wager, Rin?"

Wager. The wager.

Either Mephisto would win and Rin could have Amaimon, or Rin would win and Amaimon could have him. There was no way he would lose in either scenario.

"Yes," Rin hissed around the blood coating his mouth as he shoved back onto Mephisto's fingers, impatient for him to begin.

"Very well."

His torture ended, Mephisto withdrawing his fingers and pushing into him immediately after.

He'd placed one hand at Rin's hip and the other pressed flat to his chest over his heart.

Then he began to move.

_Finally_. Rin cried out, releasing Mephisto's neck and arching his head back, sightless as Mephisto filled him in a relentless pace.

With each passing moment, another scream of a dying demon carried through the air to them, followed by the trembling earth that hadn't stopped shaking Rin's body.

Though at this point he couldn't tell if he shook from the way Mephisto's brutal thrusts wound him into new heights of pleasure or because of Amaimon.

Even when Mephisto constricted their tails in a writhing dance that sent jolts verging on painful up Rin's spine, he couldn't keep his eyes off Amaimon's violent warpath.

Rin wanted to lose the wager, he wanted to win it. He didn't know if he wanted to claim Amaimon or be claimed in turn.

Both.

Or maybe- Rin gasped as Mephisto scraped fangs to his shoulder- maybe he would satisfy both urges.

Taking Amaimon while Mephisto had him or-

The thought that struck him made Rin moan, unable to stop the image that rose to the surface.

-Or maybe he would take Mephisto while Amaimon claimed him, depending on the outcome of the wager.

Suddenly, thoughts of sinking into Mephisto, of having him like Mephisto had him right now, filled every corner of Rin's mind.

He'd never wanted anything so bad in his life like he wanted to destroy Mephisto, wanted him gasping and trembling beneath him until he was the same mess he'd made of Rin.

And then…

Mephisto didn't let him complete the thought, forcing his legs apart and jostling him into a better position.

Then it was a struggle to keep his eyes open so he could continue watching Amaimon, Mephisto having heard his cry and knowing he'd found the right angle.

But Rin squinted through the sweat stinging his eyes and lost track of the way his mouth had dropped open, heedless of the saliva coating his chin.

Amaimon loosed a roar that had Rin keening in automatic response as it crossed the expanse to send tension singing through his nerves.

"Rin- hah- you have- _ah_\- little time left to decide," Mephisto panted as he spoke into Rin's ear, voice guttural and sending Rin's pulse spiking, "do you want to take, or be taken?"

What? Rin couldn't think, feeling Mephisto fill him in an increasingly erratic pace. Then he realized the cries of the demons around them had lessened. Amaimon was almost finished.

And so was Mephisto.

Take, or be taken? Win or lose the wager?

Fangs made the suggestion of a bite at his shoulder, letting Rin know Mephisto was close.

A shriek of desperation shocked Rin from his contemplation, head jerking to the side to see some demons had gotten through Amaimon's defense, bearing down on he and Mephisto.

Rin sneered at them, at their weakness. He let his flames loose, an expanding circle of blue that incinerated the demons and everything in the vicinity.

Power absolute that such creatures couldn't hope to comprehend.

Only he and Mephisto survived at the center of the inferno.

The energy stroked along Mephisto's body, Rin grinning at the groan pressed into his skin and the tangled bangs itching where Mephisto dropped his head against him.

Take.

He'd decided, reaching to grab the base of Mephisto's tail and yanking to hear the cry it got for his efforts.

Mephisto sank his fangs into Rin a moment later, coming in hot bursts Rin hardly felt within the heat of his own flames.

And Amaimon still had demons on the field to finish off.

Good. Rin let a pleased smile slice across his face, tongue coming out to trace at his lips and gaze pinned to the swift form cutting through the last of the horde.

Rin prised the limbs from his body, hearing the startled breath when he pulled Mephisto's head back by the hair.

"I'm going to _take_ him, Mephisto," Rin growled against the open mouth before claiming Mephisto in a bloody kiss.

He drew away with a last sharp nip to Mephisto's lips, satisfied when he saw the dazed expression that tracked him as he stalked towards Amaimon.

Every step closer to Amaimon had his grin widening until it bared jagged fangs at the unsuspecting form he couldn't wait to dig them into.

Only a handful of demons surrounded Amaimon now, the few strongest summoned by Rin's heat.

Massive tail lashing behind him and deceptively relaxed reptilian claws at his sides, Amaimon seemed to be sizing his opponents up.

Rin didn't have that patience. He wanted Amaimon's focus on _him_, only on him.

With a thought, blue flames lit in a ring around Amaimon, covering whatever shocked noises he may have made with the death cries of the last of the demons.

But he still got treated to the sight of luminous gold eyes, slit pupils blown in them, when Amaimon wrenched his body to face Rin.

"Amaimon," Rin crooned, voice calling over the crackling fire to make Amaimon twitch, at immediate attention. "I won the wager, Amaimon so-"

Three steps that blackened the broken ground beneath Rin's feet and he was upon Amaimon.

His hands reached to caress Amaimon's slackened blood and grit stained cheeks.

"-So I get to have you, Amaimon," Rin finished, pressing his body up to Amaimon's and letting the flames lick the filth from his shivering skin.

Clothing burned after, ashes drifting up as glowing cinders into the fire spout Rin created.

Amaimon's fluttering pulse in his throat called Rin to rest his lips there, whispering his next words.

"Will you let me, Amaimon?"

Pulse jolting at his words and body jerking against him, Amaimon hadn't stopped staring. Rin didn't think he'd breathed since he'd been enveloped in his fire.

"Amaimon," Rin said again, brushing his thumbs to the face he still held.

Then he gave his command.

"_Kneel_."

The word hadn't finished leaving his mouth but Amaimon's knees hit the ground like his strings had been cut.

It brought the smile back to Rin as he let his hands drop to card through the hair his flames tossed around Amaimon's head.

Those clawed hands rose to Rin's hips, engulfing his tapered waist while Amaimon leant forward with eyelids shuttering over glazed eyes.

His cheek settled to Rin's stomach in supplication and waited for his next command.

So Rin gave him one.

"On your back, Amaimon."

Seeing the vulnerable expanse of Amaimon's body bared to him sent a shiver of pleasure down Rin. He took his time drinking in the sight, of the way Amaimon twitched at each slow pass of his gaze.

Then Rin smiled, rolling his neck before kneeling in turn to straddle Amaimon.

Inhaling into the crook of the offered throat sent a purr rumbling through him as he savored the sweet scent.

Small gasps teased at his ears when he refused to hurry things along, even when Rin could see Amaimon desperately wanted to move beneath his touches.

Power and the threat of Rin's flames kept him quivering like a too-tight string that had just been plucked.

How long could he keep him like this? How long before Amaimon's own instincts pushed him to rebel?

Rin wanted to test it out.

Gold eyes caught his, a silent plea on Amaimon's normally stoic face.

The haze cleared somewhat at the entreaty and then it was Rin's own desires that had him claiming the lips under his in a searing kiss.

Grinding down onto Amaimon's hips was the cue he needed to break out of his paralysis, rising to meet Rin and groaning into his mouth.

Now he just had to remember what he'd learned, what they'd both taught him during the week, and apply it.

He'd always been a hands-on learner.

Getting to hear Amaimon gasp and watch his eyes roll back in his skull while Rin prepared him was something he hadn't known he'd needed until then.

An added element of interest absorbed Rin as the reptilian hands dug furrows into the earth, dangerous enough to gut him if Amaimon attacked.

And the thick, scaled tail that lashed between Amaimon's legs made Rin wonder if it was just as sensitive as usual.

Why hold himself back? Rin reached with the hand not inside Amaimon to palm his writhing tail.

"_Nng_-!" Amaimon choked on his breath, tongue lolling out around elongated fangs while his head tossed to either side as if to escape the sensation.

Pre-come leaked onto his stomach, Rin bent to lick it away.

With his tongue still tracing at the dips of the solid muscle, Rin glanced up beneath his lashes to see Amaimon fixated on what he was doing.

He crooked his fingers and Amaimon shouted, head jerking to the ground and chest arching like he'd been electrocuted. Rin had found the spot, it seemed.

Rubbing it a few more times in experiment had the instincts in Rin perking up, a satisfied rumble going through him as Amaimon whimpered at his merciless touch.

But he wanted to hear all the sounds Amaimon could make, that he could pull from him with his touch.

So Rin let his flames die until only the environment smoldered.

A shift of gravel in front of Rin made him look up and growl, lip curling over a fang to see Mephisto now standing a few feet from them.

At his warning, Mephisto backed off another few feet before Rin was satisfied with his distance.

Continued whimpering brought Rin back to Amaimon, though it was to find his face turned to Mephisto like he was pleading with him.

"Amaimon," Rin said, dark and dangerous enough that Amaimon flinched under him, "look at me."

Those desperate eyes turned on Rin and, without his flames to cover them, all the small gasps Amaimon released toyed with his senses.

"Good, Amaimon," Rin granted him, smiling as he rewarded the behavior with another firm stroke along Amaimon's tail.

Although, by the way Amaimon once again froze as if stricken beneath him at the pleasure coursing through his body, Rin wasn't sure if he considered it a reward.

"I had no idea what a cruel little monster a rut would turn you into, Rin," Mephisto said, breaking him from where he idly pressed at that spot in Amaimon to see if he could get him to choke on a scream again.

Monster? Rin narrowed his eyes, what did he-?

"This is quite a different punishment for his actions tonight than I had in mind," green eyes glinted while Mephisto's lips parted around needle sharp teeth, "he may have preferred the instant death of his vessel to this drawn out torture you're subjecting him to."

Torture? Amaimon's cries pierced more of the haze, Rin blinking. Then he noticed what looked like tears at the corners of Amaimon's eyes, put there by the way Rin held him on the edge, by the way Rin played with him.

Achingly hard by now, body flushed and sweating, and pre-come gathering at his taut stomach while his chest heaved in gasping breaths, Amaimon had become a wreck beneath Rin.

He'd wanted to see how long he could tease him before he broke, but now- Rin flicked his gaze up to Mephisto- now he just wanted to take Amaimon while Mephisto watched.

When Amaimon screamed for him, then Mephisto would know who he belonged to.

And then- Rin ran his tongue just besides Amaimon's length, pinning Mephisto in his gaze- then later he would show Mephisto who _he_ belonged to.

Now, though, now he would have Amaimon's screams.

Rin removed his fingers from Amaimon, still keeping watch on Mephisto so he could see the way his pupils slivered in his eyes and his fangs fill his mouth as his claws flexed at his sides

Each deliberate move from Rin ramped up the tension, electrifying the air between them over Amaimon's body.

Lining himself up with Amaimon's entrance had legs parting for him on automatic, hips tilted and spine arched like Amaimon would impale himself all on his own if Rin wouldn't.

Instead, Rin leaned over, nipping to draw blood at Amaimon's ear and eliciting more of those addictive sounds.

"Amaimon," he said, voice a sly murmur while his claws traveled up Amaimon's flank to his jugular, "ask me, Amaimon."

Ask him so that Mephisto could hear it, Rin completed in his head, though by the way Mephisto's head drew back, the message was well received.

Could Amaimon even comprehend him at this point? Rin would have to be more convincing.

"Amaimon," he growled straight into the pointed ear as his chest vibrated against Amaimon's.

"_Beg_."

Gold eyes shot open, mouth gaping in a long whine that echoed in the air.

"_Rin_\- please, Rin!"

Mephisto had _definitely_ heard that. Rin smiled, impish, up at the warping features on Mephisto's face as he was forced to listen to the stream of pleas from Amaimon.

"Thank you, Amaimon," Rin said as he nuzzled into Amaimon, then licked at his cheek in reward. If it allowed Rin to taste the tears that had escaped at his order, then it counted as a reward for him, too.

It also gave him the perfect view of Amaimon's expression as he sank into him, his true reward.

Legs wrapped around his hips, Amaimon already trying to get him in further as his head arched to the ground, giving Rin better access to bite at his neck.

His attentions soon had blood joining the sweat Rin lapped off the exposed throat.

The way Amaimon enveloped him, wet heat squeezing Rin with each drag of his length inside, had Rin realizing why they had been so enamoured when doing the same to him throughout the week.

What else had they done?

Oh yeah.

Rin gripped one of Amaimon’s thighs, claws drawing red lines that he happily cleaned, the shout it got out of Amaimon and hiss from Mephisto making him purr as he tested Amaimon’s flexibility.

Pushing at the captured thigh, Rin discovered that Amaimon was _very_ flexible.

So he did the same with the other leg until he had Amaimon nearly folded in two and moaning when Rin slammed to his hips in response.

Only then did Rin allow himself to get lost in the rhythm pounding through his veins.

Everything but the way Amaimon felt under him, around him, the way their bodies fit together- it all washed away.

Rin increased his pace, suddenly fixated on what it would feel like to be the one filling and claiming for once and feeling himself getting close.

The shoulder every thrust from Rin shoved into the ground began to look like an invitation.

He accepted.

His forehead dropped, Rin bowing over Amaimon without conscious thought to clamp his fangs into the muscle and bite.

"_Ah_!"

Amaimon shouted, voice hoarse, and clenched around Rin as he came.

Release hit Rin, sliding down his chest as he moaned into the bite until he joined Amaimon, hands bruising as he held him in place so he could finish.

"Mmn, _mine_," Rin hummed into the healing mark, an energy thrumming between he and Amaimon and settling in their cores.

It made him want to lick and bite and suck at every part of Amaimon until he'd reached that glowing core contained within his vessel.

It made him want to consume Amaimon utterly.

Could he? Rin paused where he’d been alternating between gnawing and mouthing at his claim.

Why not? Amaimon was his to do with whatever he wanted.

Fangs filled his mouth to their full capacity, bristling wedges more like a shark’s than anything else as Rin nosed to the now healed shoulder.

A warning sound reached him from Mephisto just as Rin opened his jaws, fixed his claws into Amaimon’s thighs, and tore a chunk from his neck.

“_Ahhhhh_!”

Mephisto’s abrupt curse meant nothing to Rin.

But Amaimon’s shriek of pain and sudden wild bucking beneath him- not, as he had earlier, in an attempt to get closer to Rin, but to escape him- brought Rin back to himself in a wash of cold clarity.

It was too late, the section of flesh he’d taken from Amaimon already moved down his gullet by the time Rin could yank himself back and off of Amaimon.

He scuttled away on all fours, eyes wide and unable to leave the sight of Amaimon’s form where it curled on the ground, tail coming up as if to shield himself from another attack.

Rin gagged, hand at his mouth only to jerk it off when he felt the sticky blood there.

“Well, I’d say Amaimon has learned his lesson, wouldn’t you, Rin?”

“I’m sorry!” Rin said, horror at his actions sending his heart racing with dread and not helped in the slightest by Mephisto’s teasing.

Mephisto snorted, coming to stand over where Amaimon finally calmed his thrashings to stare up with new tears in his eyes.

“Trust me, Rin, he’s more than fine.”

“I just _ate_ him- I hurt him!” Rin snapped, jabbing a finger at Mephisto and getting angry when it just got him a laugh.

The reptilian features withdrew from Amaimon, leaving his shoulder bared to Rin's frantic gaze. Already, the hole had mostly filled, healing at the same rapid pace Rin did.

"See? Nothing to get excited about," Mephisto said with an unnecessary gesture when Amaimon stood to blink at Rin with his usual blank expression like nothing had happened.

Well, that wasn't entirely true, Amaimon still sported flushed cheeks and he seemed _too_ focused on Rin.

At the lack of any kind of normal reaction from Mephisto or Amaimon, Rin groaned, dropping to the ground and rubbing his eyes with his palms.

"What the hell was that?" Rin mumbled the question, almost hoping it would go unanswered.

Movement from one of the two made Rin's ears twitch and he began to take his hands from his eyes only to gasp.

"Oof!" Rin grunted, looking up, startled, into Amaimon's inquisitive gold eyes.

"Why?" He whimpered out, giving up on feeling guilty if Amaimon was just going to respond by jumping him.

Amaimon dropping the rest of the way to press the tip of his nose to Rin's just solidified his decision- totally lost and blushing at what could be mistaken for affection.

"You're in _rut_," Amaimon said, repeating the word Rin vaguely remembered Mephisto saying, not that he understood it any more the second time.

"That doesn't actually mean anything to me." Rin tried to be upset, he really did. But Amaimon's expression of fascination made it shallow.

"It means your heat has officially ended, Rin, you should be happy," came Mephisto's voice from over Amaimon's shoulder where he now beamed at them from.

"Why did I feel like that then, and why did I do that to Amaimon?"

Was that a _purr_ from Amaimon? Rin glared at the smirk now painting Mephisto's face while Amaimon wriggled in his lap. He did bring his arms up to wrap over Amaimon's shoulders, though, something in him having grown to enjoy the closeness after the week he'd been through.

"It’s the opposite of a heat- though usually demons don’t experience one right after the other, you’re just lucky, I suppose,” Mephisto said, knowing full well that “lucky” wasn’t the word Rin would use to describe his situation.

“Okay and?” Rin huffed an impatient breath out, rolling his eyes at the lost cause of trying to get Mephisto to pretend at sympathy, “what’s gonna happen now? How long’s it gonna last?”

“Who knows!” Mephisto said- chirped, really, hands coming up in an exaggerated shrug with a cheery smile on his face that Rin scowled at. “This is unprecedented.”

“It means we can keep playing, Rin,” Amaimon added, making Rin shiver when his lips brushed his throat where he’d tucked his face into.

Rin let out a controlled exhale through his nose, eyes closing as he accepted his fate, “fine, great, can we go back, now? And can you guys tell er- that guy, Bel-something? Tell him I’m sorry.”

Amaimon rose off of him with a last lick at his skin that made Rin have to ignore another shiver from his body, following him up and groaning at the ache in his back from the hard ground.

“Oh, you can always tell Belial yourself, now, Rin,” Mephisto said, and Rin was instantly suspicious.

“Isn’t he supposed to stay away from me because I’ll try to kill him or something?” Rin said, biting the clear bait from Mephisto with crossed arms to show he knew there was a catch.

Yep, there was the shit-eating grin on Mephisto’s face now.

“That was a heat, Rin, now you’ll just want to claim him, and he’ll be able to survive that- minus a few pieces after you’ve torn them out, not that any good demon would complain about such a thing.”

“Yeah, how about no, and you can tell him for me, bastard.” Rin sighed again, not even bothering to give Mephisto’s suggestion the bare minimum of a first- or second- thought.

“Spoil sport,” Mephisto replied, obviously expecting Rin’s reaction and raising a hand to snap.

“Rin, we can come here to play, now,” Amaimon said, excitement filling his words and eyes bright. By which Rin assumed he meant “fight”, the word taking on a double meaning he’d learned to interpret after so much exposure to Amaimon.

Rin’s irritation broke, wry smile coming out in answer and ruffling his mussed hair in the face of Amaimon’s enthusiasm.

“Yeah, okay, Amaimon, we can play.”

The snap came, taking them from the devastated field.

Then, Rin readied himself for who knew how long of dealing with his newest demonic issue.

Glancing at Amaimon as they followed Mephisto to the bathroom for a shower, Rin found he wasn’t feeling the disappointment he would have when the whole thing began.

In fact, it was something more like anticipation coloring his mood.

But they didn’t need to know that.

Yet, at least.

**Author's Note:**

> Why yes, I did think this would be a fun, possibly 10k fic. I was at least able to keep it to only double that length, I guess :D 
> 
> ...And had to fight very hard to resist writing Rin's week-long rut where he gets to pay back his two bastards in full for what he went through in this fic so I could get back to BRS lol
> 
> Let me know how you guys liked this one~


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